Organic Electroluminescent Device; A Charge Transporting Material For The Organic Electroluminescent Device; And A Luminescent Device, A Display Device And A Lighting System Using The Organic Electroluminescent Device

ABSTRACT

An organic electroluminescent element comprising a substrate; a pair of electrodes including an anode and a cathode, disposed on the substrate; and at least one organic layer including a light emitting layer, disposed between the electrodes, wherein the light emitting layer includes a compound represented by the following general formula: 
     
       
         
         
             
             
         
       
     
     (R 1 , R 2 , and R 19  each independently represent a hydrogen atom, a phenyl group, a monovalent oligoaryl group having the number of rings of from 2 to 10, or a monovalent fused polycyclic aromatic hydrocarbon group having the number of rings of from 2 to 6, provided that at least one of R 1 , R 2 , and R 19  represents a monovalent oligoaryl group having the number of rings of from 2 to 10 or a monovalent fused polycyclic aromatic hydrocarbon group having the number of rings of from 2 to 6, and that the phenyl group, the monovalent oligoaryl group having the number of rings of from 2 to 10, and the monovalent fused polycyclic aromatic hydrocarbon group having the number of rings of from 2 to 6 do not have an amino group as a substituent; R 11  to R 18  each independently represent a hydrogen atom or a substituent; and A 1  to A 4  each independently represent a nitrogen atom or a carbon atom, provided that when A 1  to A 4  are a nitrogen atom, R 1  and R 11  to R 13  connecting to the nitrogen atom do not exist.)

FIELD OF THE INVENTION

The present invention relates to an organic electroluminescent element,a charge transporting material for an organic electroluminescentelement, and a light emitting device, a display device and anillumination device each using the element.

BACKGROUND OF INVENTION

Since organic electroluminescent elements (which may hereinafter also bereferred to as “elements” or “organic EL elements”) are capable ofhigh-luminance light emitting using low voltage driving, they have beenactively researched and developed. The organic electroluminescentelements have a pair of electrodes and an organic layer between the pairof electrodes, and utilize, for light emitting, energy of the excitongenerated as a result of recombination of the electron injected from thecathode and the hole injected from the anode in the organic layer.

In recent years, high efficiency in organic electroluminescent elementsis being advanced by using a phosphorescent material. However, inpractical implementation, improvements are demanded from the viewpointsof a lowering of driving voltage and durability.

On the other hand, organic electroluminescent elements using, as a hostmaterial of the light emitting layer, a compound having a structure inwhich phenyl groups of triphenylamine are connected to each other andfused to from a carbazole ring or the like are known.

Patent Document 1 describes an organic electroluminescent element using,as a host material of the light emitting layer, a material having astructure in which benzene rings of a triphenylamine are mainlyconnected to each other via a methylene chain or the like and combiningit with a phosphorescent material, and it can be read from PatentDocument 1 that high efficiency, low voltage, and element durability aregreatly enhanced. As for the means of connecting the benzene rings of atriphenylamine to each other, Patent Document 1 does not describe that asingle bond is particularly excellent.

On the other hand, Patent Document 2 describes an organicelectroluminescent element using, as a host material of the lightemitting layer, a compound having a structure analogous to that inPatent Document 1 and combining it with a phosphorescent material andreports that when formed into an element capable of undergoing redphosphorescence emission, high efficiency and low voltage are achieved.Though Patent Document 2 describes various compounds in which benzenerings of a triphenylamine are connected to each other via a methylenechain or a single bond, it does not describe any compound in whichbenzene rings of a triphenylamine are connected to each other via two ormore single bonds.

Patent Document 3 describes a compound having a structure in which twophenyl groups of triphenylamine are connected to each other and fusedand describes that by using this compound as a host material of thelight emitting layer, an organic electroluminescent element with goodluminous efficiency and low driving voltage can be provided. ThoughPatent Document 3 describes some compounds having an indolocarbazoleskeleton in which benzene rings of a triphenylamine are connected toeach other via two single bonds, it does not describe anyindolocarbazole having an oligoaromatic hydrocarbon ring as asubstituent.

RELATED ART DOCUMENTS Patent Documents [Patent Document 1] WO2007/031165[Patent Document 2] WO2010/050778 [Patent Document 3] JP-A-2010-087496

However, Patent Document 1 reports the element durability regarding onlyblue-emitting elements. In addition, Patent Documents 1 to 3 inclusiveof Patent Document 1 neither disclose nor suggest how the luminance isdeteriorated particularly at the initial light time. In this respect,the present inventors investigated characteristics of the organicelectroluminescent elements described in Patent Documents 1 to 3. As aresult, it was noted that dissatisfaction remains from the viewpoint ofa luminance deterioration rate at the initial stage of lighting; andthat dissatisfaction also remains on long-term durability until theluminance reduces by half. In particular, the matter that the luminancedeterioration of an organic electroluminescent element at the initialstage of lighting is fast is not so problematic in the case of use forsimple illumination, the use of which is in general not advanced due toissues of cost. However, it was noted that, for example, when such anelement in which the luminance deterioration at the initial stage oflighting is fast is used as alight source of green of a display, adifference in the luminance deterioration rate at the initial stage oflighting from a red or blue light source is generated, resulting in aproblem of color shift exceeding a range of assumption at the time ofmanufacture of a usual display. That is, it was noted that when abruptluminance deterioration at the initial stage of lighting occurs,although such abrupt luminance deterioration is hardly perceived in thecase of a single color, when the color is mixed with other colors as ina display application or the like, it is perceived as a color shift,resulting in a problem.

An object of the present invention is to provide an organicelectroluminescent element having a slow luminance deterioration rate atthe initial stage of lighting and excellent long-term durability.

BRIEF SUMMARY OF THE INVENTION

As a result of extensive and intensive investigations made by thepresent inventors, it has been found that by using a material having aspecified substituent that is a hydrocarbon aromatic group at aspecified position of an indolocarbazole skeleton, it is possible toprovide an organic electroluminescent element having a slow luminancedeterioration rate at the initial stage of lighting and excellentlong-term durability.

Measures for solving the above-described problems are as follows.

[1] An organic electroluminescent element comprising a substrate; a pairof electrodes including an anode and a cathode, disposed on thesubstrate; and at least one organic layer including a light emittinglayer, disposed between the electrodes, wherein the light emitting layerincludes a compound represented by the following general formula (1):

(In the general formula (1), R¹, R², and R¹⁹ each independentlyrepresent a hydrogen atom, a phenyl group, a monovalent oligoaryl grouphaving the number of rings of from 2 to 10, or a monovalent fusedpolycyclic aromatic hydrocarbon group having the number of rings of from2 to 6, provided that at least one of R¹, R², and R¹⁹ represents amonovalent oligoaryl group having the number of rings of from 2 to 10 ora monovalent fused polycyclic aromatic hydrocarbon group having thenumber of rings of from 2 to 6, and that the phenyl group, themonovalent oligoaryl group having the number of rings of from 2 to 10,and the monovalent fused polycyclic aromatic hydrocarbon group havingthe number of rings of from 2 to 6 do not have an amino group as asubstituent; R¹¹ to R¹⁸ each independently represent a hydrogen atom ora substituent; and A¹ to A⁴ each independently represent a nitrogen atomor a carbon atom, provided that when A¹ to A⁴ are a nitrogen atom, R¹and R¹¹ to R¹³ connecting to the nitrogen atom do not exist.)

[2] The organic electroluminescent element as set forth in [1], whereinthe compound represented by the general formula (1) is preferably acompound represented by the following general formula (2):

(In the general formula (2), R¹ and R² each independently represent ahydrogen atom, a phenyl group, a monovalent oligoaryl group having thenumber of rings of from 2 to 10, or a monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6,provided that at least one of R¹ and R² represents a monovalentoligoaryl group having the number of rings of from 2 to 10 or amonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6, and that the phenyl group, the monovalentoligoaryl group having the number of rings of from 2 to 10, and themonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6 do not have an amino group as a substituent; andR¹¹ to R¹⁸ each independently represent a hydrogen atom or asubstituent.)

[3] The organic electroluminescent element as set forth in [1], whereinthe compound represented by the general formula (1) is preferably acompound represented by the following general formula (3):

(In the general formula (3), R² represents a hydrogen atom, a phenylgroup, a monovalent oligoaryl group having the number of rings of from 2to 10, or a monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6, and the phenyl group, themonovalent oligoaryl group having the number of rings of from 2 to 10,and the monovalent fused polycyclic aromatic hydrocarbon group havingthe number of rings of from 2 to 6 do not have an amino group as asubstituent; and R¹¹ to R¹⁸, R²¹ to R²⁵, and R³¹ to R³⁵ eachindependently represent a hydrogen atom or a substituent, provided thatR² represents a monovalent oligoaryl group having the number of rings offrom 2 to 10 or a monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6, at least one of R²¹ to R²⁵and R³¹ to R³⁵ represents an aryl group, or two or more of R²¹ to R²⁵ ortwo or more of R³¹ to R³⁵ are bound to each other to form a fusedpolycyclic aromatic hydrocarbon ring having the number of rings of from2 to 6.)

[4] The organic electroluminescent element as set forth in [1], whereinthe compound represented by the general formula (1) is preferably acompound represented by the following general formula (4):

(In the general formula (4), R¹, R², and R¹⁹ each independentlyrepresent a hydrogen atom, a phenyl group, a monovalent oligoaryl grouphaving the number of rings of from 2 to 10, or a monovalent fusedpolycyclic aromatic hydrocarbon group having the number of rings of from2 to 6, provided that at least one of R¹, R², and R¹⁹ represents a groupselected from the following general formulae (CH-1) to (CH-11), and thatthe phenyl group, the monovalent oligoaryl group having the number ofrings of from 2 to 10, and the monovalent fused polycyclic aromatichydrocarbon group having the number of rings of from 2 to 6 do not havean amino group as a substituent; and R¹¹ to R¹⁸ each independentlyrepresent a hydrogen atom or a substituent.)

(In the general formulae (CH-1) to (CH-11), * represents a bindingsite.)

[5] The organic electroluminescent element as set forth in any one of[1] to [4], wherein, in the general formula (1), the group representedby R¹ or R² is preferably a group containing only one p-phenylene group.[6] The organic electroluminescent element as set forth in any one of[1] to [5], wherein the light emitting layer preferably further containsa phosphorescent material.[7] The organic electroluminescent element as set forth in [6], whereinthe phosphorescent material is preferably an iridium complex.[8] The organic electroluminescent element as set forth in [7], whereinthe iridium complex is preferably represented by the following generalformula (E-1):

(In the general formula (E-1), Z¹ and Z² each independently represent acarbon atom or a nitrogen atom; A¹ represents an atomic group forforming a 5- or 6-membered heterocyclic ring together with Z¹ and thenitrogen atom; B¹ represents an atomic group for forming a 5- or6-membered heterocyclic ring together with Z² and the carbon atom; (X—Y)represents a monoanionic bidentate ligand; and n_(E1) represents aninteger of from 1 to 3.)

[9] The organic electroluminescent element as set forth in [8], whereinthe iridium complex represented by the general formula (E-1) ispreferably represented by the following general formula (E-2):

(In the general formula (E-2), A^(E1) to A^(E8) each independentlyrepresent a nitrogen atom or C—R^(E); R^(E) represents a hydrogen atomor a substituent; (X—Y) represents a monoanionic bidentate ligand; andn_(E2) represents an integer of from 1 to 3.)

[10] The organic electroluminescent element as set forth in any one of[7] to [9], wherein the iridium complex represented by the generalformula (E-1) is preferably the following compound:

[11] The organic electroluminescent element as set forth in any one of[1] to [10], wherein the compound represented by the general formula (1)preferably has a molecular weight of not more than 800.[12] The organic electroluminescent element as set forth in any one of[1] to [11], wherein the light emitting layer is preferably formed by avacuum deposition process.[13] The organic electroluminescent element as set forth in any one of[1] to [11], wherein the light emitting layer is preferably formed by awet process.[14] A charge transporting material for an organic electroluminescentelement represented by the following general formula (1):

(In the general formula (1), R¹, R², and R¹⁹ each independentlyrepresent a hydrogen atom, a phenyl group, a monovalent oligoaryl grouphaving the number of rings of from 2 to 10, or a monovalent fusedpolycyclic aromatic hydrocarbon group having the number of rings of from2 to 6, provided that at least one of R¹, R², and R¹⁹ represents amonovalent oligoaryl group having the number of rings of from 2 to 10 ora monovalent fused polycyclic aromatic hydrocarbon group having thenumber of rings of from 2 to 6, and that the phenyl group, themonovalent oligoaryl group having the number of rings of from 2 to 10,and the monovalent fused polycyclic aromatic hydrocarbon group havingthe number of rings of from 2 to 6 do not have an amino group as asubstituent; R¹¹ to R¹⁹ each independently represent a hydrogen atom ora substituent; and A¹ to A⁴ each independently represent a nitrogen atomor a carbon atom, provided that when A¹ to A⁴ are a nitrogen atom, R¹and R¹¹ to R¹³ connecting to the nitrogen atom do not exist.)

[15] The charge transporting material for an organic electroluminescentelement as set forth in [14], wherein the compound represented by thegeneral formula (1) is preferably a compound represented by thefollowing general formula (2):

(In the general formula (2), R¹ and R² each independently represent ahydrogen atom, a phenyl group, a monovalent oligoaryl group having thenumber of rings of from 2 to 10, or a monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6,provided that at least one of R¹ and R² represents a monovalentoligoaryl group having the number of rings of from 2 to 10 or amonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6, and that the phenyl group, the monovalentoligoaryl group having the number of rings of from 2 to 10, and themonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6 do not have an amino group as a substituent; andR¹¹ to R¹⁸ each independently represent a hydrogen atom or asubstituent.)

[16] The charge transporting material for an organic electroluminescentelement as set forth in [14], wherein the compound represented by thegeneral formula (1) is preferably a compound represented by thefollowing general formula (3):

(In the general formula (3), R² represents a hydrogen atom, a phenylgroup, a monovalent oligoaryl group having the number of rings of from 2to 10, or a monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6, and the phenyl group, themonovalent oligoaryl group having the number of rings of from 2 to 10,and the monovalent fused polycyclic aromatic hydrocarbon group havingthe number of rings of from 2 to 6 do not have an amino group as asubstituent; and R¹¹ to R¹⁸, R²¹ to R²⁵, and R³¹ to R³⁵ eachindependently represent a hydrogen atom or a substituent, provided thatR² represents a monovalent oligoaryl group having the number of rings offrom 2 to 10 or a monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6, at least one of R²¹ to R²⁵and R³¹ to R³⁵ represents an aryl group, or two or more of R²¹ to R²⁵ ortwo or more of R³¹ to R³⁵ are bound to each other to form a fusedpolycyclic aromatic hydrocarbon ring having the number of rings of from2 to 6.)

[17] The charge transporting material for an organic electroluminescentelement as set forth in [14], wherein the compound represented by thegeneral formula (1) is preferably a compound represented by thefollowing general formula (4):

(In the general formula (4), R¹, R², and R¹⁹ each independentlyrepresent a hydrogen atom, a phenyl group, a monovalent oligoaryl grouphaving the number of rings of from 2 to 10, or a monovalent fusedpolycyclic aromatic hydrocarbon group having the number of rings of from2 to 6, provided that at least one of R¹, R², and R¹⁹ represents a groupselected from the following general formulae (CH-1) to (CH-11), and thatthe phenyl group, the monovalent oligoaryl group having the number ofrings of from 2 to 10, and the monovalent fused polycyclic aromatichydrocarbon group having the number of rings of from 2 to 6 do not havean amino group as a substituent; and R¹¹ to R¹⁸ each independentlyrepresent a hydrogen atom or a substituent.)

(In the general formulae (CH-1) to (CH-11), * represents a bindingsite.)

[18] The charge transporting material for an organic electroluminescentelement as set forth in any one of [14] to [17], wherein, in the generalformula (1), the group represented by R¹ or R² is preferably a groupcontaining only one p-phenylene group.[19] The charge transporting material for an organic electroluminescentelement as set forth in any one of [14] to [18], wherein the compoundrepresented by the general formula (1) preferably has a molecular weightof not more than 800.[20] A light emitting device using the organic electroluminescentelement as set forth in any one of [1] to [13].[21] A display device using the organic electroluminescent element asset forth in any one of [1] to [13].[22] An illumination device using the organic electroluminescent elementas set forth in any one of [1] to [13].

According to the present invention, it is possible to provide an organicelectroluminescent element having a slow luminance deterioration rate atthe initial stage of lighting and excellent long-term durability.

In addition, according to the present invention, it is further possibleto provide a light emitting device, a display device, and anillumination device each using the element.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 A schematic view showing one example of a configuration of theorganic electroluminescent element according to the present invention.

FIG. 2 A schematic view showing one example of the light emitting deviceaccording to the present invention.

FIG. 3 A schematic view showing one example of the illumination deviceaccording to the present invention.

FIG. 4 An NMR chart of Illustrative Compound 3.

DETAILED DESCRIPTION OF THE INVENTION

The details of the present invention are hereunder described. Thedescription of the configuration requirements below is based onrepresentative embodiments and specific examples of the presentinvention, but the present invention is not limited to these embodimentsand specific examples. Incidentally, in the present specification, therange expressed with “to” means a range including the numerical valuesbefore and after “to” as the lower limit and the upper limit,respectively.

[Organic Electroluminescent Element and Charge Transporting Material forOrganic Electroluminescent Element]

The charge transporting material for an organic electroluminescentelement according to the present invention comprises a compoundrepresented by the following general formula (1). By using a materialhaving a hydrocarbon aromatic substituent at a specified position of anindolocarbazole skeleton as a phosphorescent host material, it ispossible to provide an organic electroluminescent element capable ofmaking high durability and suppression of deterioration at the initialstage of lighting compatible with each other.

The organic electroluminescent element according to the presentinvention comprises a substrate; a pair of electrodes including an anodeand a cathode, disposed on the substrate; and at least one organic layerincluding a light emitting layer, disposed between the electrodes,wherein the light emitting layer includes a compound represented by thefollowing general formula (1):

(In the general formula (1), R¹, R², and R¹⁹ each independentlyrepresent a hydrogen atom, a phenyl group, a monovalent oligoaryl grouphaving the number of rings of from 2 to 10, or a monovalent fusedpolycyclic aromatic hydrocarbon group having the number of rings of from2 to 6, provided that at least one of R¹, R², and R¹⁹ represents amonovalent oligoaryl group having the number of rings of from 2 to 10 ora monovalent fused polycyclic aromatic hydrocarbon group having thenumber of rings of from 2 to 6, and that the phenyl group, themonovalent oligoaryl group having the number of rings of from 2 to 10,and the monovalent fused polycyclic aromatic hydrocarbon group havingthe number of rings of from 2 to 6 do not have an amino group as asubstituent; R¹¹ to R¹⁸ each independently represent a hydrogen atom ora substituent; and A¹ to A⁴ each independently represent a nitrogen atomor a carbon atom, provided that when A¹ to A⁴ are a nitrogen atom, R¹and R¹¹ to R¹³ connecting to the nitrogen atom do not exist.)

The configuration of the organic electroluminescent element according tothe present invention is not particularly limited. FIG. 1 shows oneexample of the configuration of the organic electroluminescent elementaccording to the present invention. An organic electroluminescentelement 10 of FIG. 1 has an organic layer between a pair of electrodes(an anode 3 and a cathode 9) on a substrate 2.

The element configuration of the organic electroluminescent element, thesubstrate, the cathode, and the anode are described in detail in, forexample, JP-A-2008-270736, and the detailed description thereon in thispatent document can be applied to the present invention.

Preferred embodiments of the organic electroluminescent elementaccording to the present invention are hereunder described in detail inthe order of the substrate, the electrodes, the organic layer, aprotective layer, a sealing enclosure, a driving method, a lightemitting wavelength, and applications.

<Substrate>

The organic electroluminescent element according to the presentinvention has a substrate.

The substrate used in the present invention is preferably a substratethat does not scatter or decay light emitted from the organic layer. Inthe case of an organic material, those having excellent heat resistance,dimensional stability, solvent resistance, electrical insulatingproperties, and processability are preferable.

<Electrodes>

The organic electroluminescent element according to the presentinvention has a pair of electrodes including an anode and a cathode,disposed on the substrate.

In view of the properties of the light emitting element, at least oneelectrode of a pair of electrodes, the anode and the cathode, ispreferably transparent or semi-transparent.

(Anode)

The anode may be usually one having a function as an electrode ofsupplying holes into an organic layer, and is not particularly limitedin terms of its shape, structure, size, or the like. Further, dependingon the use and purpose of the light emitting element, the anode can besuitably selected from the known electrode materials. As describedabove, the anode is usually provided as a transparent anode.

(Cathode)

The cathode may be usually one having a function as an electrode ofinjecting electrons to an organic layer, and is not particularly limitedin terms of its shape, structure, size, or the like. Further, dependingon the use and purpose of the light emitting element, the cathode can besuitably selected from the known electrode materials.

<Organic Layer>

The organic electroluminescent element according to the presentinvention has an organic layer disposed between the electrodes.

The organic layer is not particularly limited and can be suitablyselected depending on the use and purpose of the organicelectroluminescent element. However, the organic layer is preferablyformed on the transparent electrode or the semi-transparent electrode.In that case, the organic layer is formed on the whole surface or onesurface of the transparent electrode or the semi-transparent electrode.

The shape, the size, the thickness, and the like of the organic layerare not particularly limited and can be suitably selected depending onthe purpose.

The configuration of the organic layer, the method for forming anorganic layer, preferred embodiments of the respective layersconstituting the organic layer, and the materials used in the respectivelayers in the organic electroluminescent element according to thepresent invention are hereunder described in detail in order.

(Configuration of Organic Layer)

In the organic electroluminescent element according to the presentinvention, the organic layer preferably includes a charge transportinglayer. The charge transporting layer refers to a layer in which chargesmove when voltage is applied to the organic electroluminescent element.Specifically, examples thereof include a hole injecting layer, a holetransporting layer, an electron blocking layer, a light emitting layer,a hole blocking layer, an electron transporting layer, and an electroninjecting layer.

The organic electroluminescent element according to the presentinvention includes the light emitting layer containing a phosphorescentmaterial and other organic layer, and the light emitting layer includesthe compound represented by the general formula (1). The compoundrepresented by the general formula (1) is preferably used as a hostcompound of the light emitting layer. Furthermore, in the organicelectroluminescent element according to the present invention, theorganic layer more preferably includes the light emitting layercontaining a phosphorescent material and other organic layer. However,in the organic electroluminescent element according to the presentinvention, even in the case where the organic layer includes the lightemitting layer and other organic layer, a space between the both layersmay not be always made distinct.

In addition, in the organic electroluminescent element including anelectron transporting layer between a pair of electrodes, disposedadjacent to the cathode and further arbitrarily including a holeblocking layer adjacent to the electron transporting layer on theopposite side to the cathode, the charge transporting material for anorganic electroluminescent element according to the present invention isalso preferably contained in the electron transporting layer or the holeblocking layer.

In each of these organic layers, plural layers may be provided, and inthe case where plural layers are provided, the layers may be formed ofthe same material or may be formed of a different material in everylayer.

(Method for Forming Organic Layer)

The respective organic layers in the organic electroluminescent elementaccording to the present invention can be suitably formed by any of dryfilm forming methods such as a deposition method and a sputteringmethod, wet type film forming methods (solution coating methods) such asa transfer method, a printing method, a spin coating method, and a barcoating method.

In the organic electroluminescent element according to the presentinvention, the light emitting layer is preferably formed by a vacuumdeposition process. In addition, in the organic electroluminescentelement according to the present invention, the light emitting layer isalso preferably formed by a wet process.

(Light Emitting Layer)

The light emitting layer is a layer having a function of, uponapplication of an electric field, receiving holes from the anode, thehole injecting layer, or the hole transporting layer, receivingelectrons from the cathode, the electron injecting layer, or theelectron transporting layer, providing a recombination site of the holesand the electrons, and causing light emitting. However, the lightemitting layer in the present invention is not necessarily limited tothe light emitting by such a mechanism. The light emitting layer in theorganic electroluminescent element according to the present inventionpreferably contains, in addition to the compound represented by thegeneral formula (1), at least one phosphorescent material.

The light emitting layer in the organic electroluminescent elementaccording to the present invention may be constituted of only thecompound represented by the general formula (1) and the phosphorescentmaterial, or may be constituted as a mixed layer of the phosphorescentmaterial using the compound represented by the general formula (1) as ahost material. The phosphorescent material may be made of a single kindor two or more kinds thereof. The host material is preferably a chargetransporting material. The host material may be made of a single kind ortwo or more kinds thereof. Examples thereof include a configuration inwhich an electron transporting host material and a hole transportinghost material are mixed. Furthermore, the light emitting layer mayinclude a material which does not have charge transporting propertiesand which does not emit light.

In addition, the light emitting layer may be made of a single layer ormultiple layers of two or more layers. The respective layers may includethe same light emitting material or host material, and may also includea different material in every layer. In the case where plural lightemitting layers are present, the respective light emitting layers mayemit light in a different luminous color from each other.

The thickness of the light emitting layer is not particularly limited,but it is usually from 2 nm to 500 nm, and above all, from the viewpointof external quantum efficiency, it is more preferably from 3 nm to 200nm, and still more preferably from 5 nm to 100 nm.

(I) Compound Represented by the General Formula (1):

In the organic electroluminescent element according to the presentinvention, the light emitting layer contains the compound represented bythe general formula (1), and it is a preferred embodiment to use thecompound represented by the general formula (1) as a host material ofthe light emitting layer. Here, the host material as referred to in thepresent specification is a compound which chiefly plays a role ininjecting or transporting charges in the light emitting layer and isalso a compound which does not substantially emit light in itself. Asused herein, it is meant by the terms “which does not substantially emitlight” that the amount of light emission from the compound which doesnot substantially emit light is preferably not more than 5%, morepreferably not more than 3%, and still more preferably not more than 1%relative to the total amount of light emission in the whole of theelement.

As for the materials of the light emitting layer, the compoundrepresented by the general formula (1), the phosphorescent material, andother host material other than the compound represented by the generalformula (1) are hereunder described in order. Incidentally, in theorganic electroluminescent element according to the present invention,the compound represented by the general formula (1) may be used in otherlayer than the light emitting layer.

Not wishing to be restricted to any theory, it may be considered thatthe structure of the compound represented by the general formula (1) issmall in a structure strain, and therefore, it has excellent durability.

Furthermore, it may be considered that in view of the fact that thecompound represented by the general formula (1) has oligoaromaticsubstituents at the positions of R¹ and R² corresponding to the paraposition relative to the central nitrogen atom, a lowering of theluminance seen at the initial stage of lighting can be suppressed.Though a cause of the phenomenon wherein the luminance becomes abruptlysmall at the initial stage of lighting in this way is not elucidatedyet, it may be assumed that such a phenomenon occurs due torearrangement properties of intramembranous molecules in the lightemitting layer by application of voltage. As compared with theconventionally known compounds having a structure in which phenyl groupsof triphenylamine are connected to each other and fused, the compoundrepresented by the general formula (1) is small in a difference betweenthe molecular arrangement at the time of forming a film by deposition ora wet process (in particular, deposition) and the optimum moleculararrangement at the time of applying voltage, and therefore, it may beconsidered that the matter that the luminance becomes abruptly small atthe initial stage of lighting can be suppressed.

Preferred structures of the compound represented by the general formula(1) are hereunder described.

In the present invention, the hydrogen atom in the description of thegeneral formula (1) also includes isotopes (a deuterium atom and thelike), and the atoms constituting the substituent are also intended toinclude isotopes of the atoms.

In the present invention, the “substituent” at each occurrence may befurther substituted. For example, in the present invention, the “alkylgroup” at each occurrence includes an alkyl group substituted with afluorine atom (for example, a trifluoromethyl group), an alkyl groupsubstituted with an aryl group (for example, a triphenylmethyl group),and the like, but “an alkyl group having from 1 to 6 carbon atoms”represents one having from 1 to 6 carbon atoms, as any group alsoincluding substituted groups thereof.

In the general formula (1), R¹, R², and R¹⁹ each independently representa hydrogen atom, a phenyl group, a monovalent oligoaryl group having thenumber of rings of from 2 to 10, or a monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6,provided that at least one of R¹, R², and R¹⁹ represents a monovalentoligoaryl group having the number of rings of from 2 to 10 or amonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6, and that the phenyl group, the monovalentoligoaryl group having the number of rings of from 2 to 10, and themonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6 do not have an amino group as a substituent.

In the present specification, the “monovalent oligoaryl group having thenumber of rings of from 2 to 10” refers to a group containing from 2 to10 aryl groups crosslinked by a covalent bond. The monovalent oligoarylgroup having the number of rings of from 2 to 10 may have a substituentso far as the gist of the present invention is not deviated. In thepresent specification, the “monovalent fused polycyclic aromatichydrocarbon group having the number of rings of from 2 to 6” refers toan aryl group resulting from fusion of from 2 to 6 rings and may have asubstituent so far as the gist of the present invention is not deviated.

Examples of the substituent which the phenyl group in R¹, R², and R¹⁹may further have include an alkyl group having from 1 to 6 carbon atoms,an alkenyl group having from 2 to 6 carbon atoms, a phenyl group, anaromatic heterocyclic group having from 5 to 10 carbon atoms, an alkoxygroup having from 1 to 4 carbon atoms, a phenoxy group, a fluoro group,a silyl group, and a cyano group. Above all, an alkyl group having from1 to 6 carbon atoms, a phenyl group, an aromatic heterocyclic grouphaving from 5 to 10 carbon atoms, a fluoro group, a silyl group, and acyano group are preferable, and an alkyl group having from 1 to 3 carbonatoms, a phenyl group, an aromatic heterocyclic group having from 5 to10 carbon atoms, a fluoro group, and a silyl group are more preferable.

The monovalent oligoaryl group having the number of rings of from 2 to10 in R¹, R², and R¹⁹ is preferably a group in which from 2 to 10 phenylgroups are crosslinked by a covalent bond and connected to each other,more preferably a group in which from 2 to 6 phenyl groups arecrosslinked by a covalent bond and connected to each other, still morepreferably a group in which from 2 to 5 phenyl groups are crosslinked bya covalent bond and connected to each other, and especially preferably abiphenyl group, a p-terphenyl group, an m-terphenyl group, or aquarterphenyl group.

Above all, in the organic electroluminescent element according to thepresent invention, the monovalent oligoaryl group having the number ofrings of from 2 to 10, represented by R¹, R², or R¹⁹, is preferably agroup containing only one p-phenylene group from the viewpoint ofluminous efficiency. Incidentally, at that time, a p-terphenyl group isformed in the general formula (1).

In addition, the monovalent oligoaryl group having the number of ringsof from 2 to 10, represented by R¹, R², or R¹⁹, is preferably a groupcontaining at least one m-phenylene group, and more preferably a groupcontaining two m-phenylene groups. Furthermore, the monovalent oligoarylgroup having the number of rings of from 2 to 10, represented by R¹, R²,or R¹⁹, is preferably a group containing an m-phenylene group in aportion binding directly to a skeleton of an indolocarbazole analoguerepresented by the general formula (1).

The number of rings in R¹, R², and R¹⁹ is preferably from 2 to 5, morepreferably from 2 to 4, especially preferably 3 or 4, and moreespecially preferably 4.

Examples of the monovalent oligoaryl group having the number of rings offrom 2 to 10 in R¹, R², and R¹⁹ may further have include an alkyl grouphaving from 1 to 6 carbon atoms, an alkenyl group having from 2 to 6carbon atoms, a phenyl group, an aromatic heterocyclic group having from5 to 10 carbon atoms, an alkoxy group having from 1 to 4 carbon atoms, aphenoxy group, a fluoro group, a silyl group, and a cyano group. Aboveall, an alkyl group having from 1 to 6 carbon atoms, a phenyl group, anaromatic heterocyclic group having from 5 to 10 carbon atoms, a fluorogroup, a silyl group, and a cyano group are preferable, and an alkylgroup having from 1 to 3 carbon atoms, a phenyl group, an aromaticheterocyclic group having from 5 to 10 carbon atoms, a fluoro group, anda cyano group are more preferable.

Examples of the monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6 in R¹, R², and R¹⁹ include anaphthyl group, an anthracenyl group, a phenanthrenyl group, a pyrenylgroup, a triphenylenyl group, a chrysenyl group, a tetracenyl group, atetraphenyl group, a picenyl group, a perylenyl group, a pentaphenylgroup, a pentacenyl group, a benzopyrenyl group, a hexahelicenyl group,a hexaphenyl group, and a hexacenyl group. Above all, a naphthyl group,an anthracenyl group, a phenanthrenyl group, a pyrenyl group, and atriphenylenyl group are preferable, and a naphthyl group, an anthracenylgroup, and a phenanthrenyl group are more preferable.

Examples of the monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6 in R¹, R², and R¹⁹ may furtherhave include an alkyl group having from 1 to 6 carbon atoms, an alkenylgroup having from 2 to 6 carbon atoms, a phenyl group, an aromaticheterocyclic group having from 5 to 10 carbon atoms, an alkoxy grouphaving from 1 to 4 carbon atoms, a phenoxy group, a fluoro group, asilyl group, and a cyano group. Above all, an alkyl group having from 1to 6 carbon atoms, a phenyl group, an aromatic heterocyclic group havingfrom 5 to 10 carbon atoms, a fluoro group, a silyl group, and a cyanogroup are preferable, and an alkyl group having from 1 to 3 carbonatoms, a phenyl group, an aromatic heterocyclic group having from 5 to10 carbon atoms, a fluoro group, and a cyano group are more preferable.

Of these, in the case where a luminous color from the organicelectroluminescent element is green (emission peak wavelength: 490 to580 nm), R¹, R², and R¹⁹ do not preferably have a fused ring from theviewpoint of luminous efficiency namely R¹, R², and R¹⁹ are preferably ahydrogen atom, a phenyl group, or a monovalent oligoaryl group havingthe number of rings of from 2 to 10, and more preferably a hydrogen atomor a monovalent oligoaryl group having the number of rings of from 2 to10.

Furthermore, it is especially preferable that only one of R¹, R², andR¹⁹ is a monovalent oligoaryl group having the number of rings of from 2to 10, and it is more especially preferable that only one of R¹, R², andR¹⁹ is a monovalent oligoaryl group having the number of rings of from 2to 10, and the other one of R¹, R², and R¹⁹ is a hydrogen atom or aphenyl group.

In the general formula (1), R¹¹ to R¹⁸ each independently represent ahydrogen atom or a substituent; and A¹ to A⁴ each independentlyrepresent a nitrogen atom or a carbon atom, provided that when A¹ to A⁴are a nitrogen atom, R¹ and R¹¹ to R¹³ connecting to the nitrogen atomdo not exist.

In the general formula (1), examples of the substituent represented byR¹¹ to R¹⁸ independently include those in Substituent Group A asdescribed below. The substituent may further have a substituent.Examples of the further substituent include groups selected from theSubstituent Group A.

<<Substituent Group A>>

An alkyl group (having preferably from 1 to 30 carbon atoms, morepreferably from 1 to 20 carbon atoms, and especially preferably from 1to 10 carbon atoms; for example, methyl, ethyl, n-propyl, isopropyl,t-butyl, n-hexyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl,cyclopentyl, cyclohexyl, and trifluoromethyl), an alkenyl group (havingpreferably from 2 to 30 carbon atoms, more preferably from 2 to 20carbon atoms, and especially preferably from 2 to 10 carbon atoms; forexample, vinyl, allyl, 2-butenyl, and 3-pentenyl), an alkynyl group(having preferably from 2 to 30 carbon atoms, more preferably from 2 to20 carbon atoms, and especially preferably from 2 to 10 carbon atoms;for example, propargyl and 3-pentynyl), an aryl group (having preferablyfrom 6 to 30 carbon atoms, more preferably from 6 to 20 carbon atoms,and especially preferably from 6 to 14 carbon atoms; for example,phenyl, p-methylphenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl,naphthyl, anthranyl, and triphenylenyl), an amino group (havingpreferably from 0 to 30 carbon atoms, more preferably from 0 to 20carbon atoms, and especially preferably from 0 to 10 carbon atoms; forexample, amino, methylamino, dimethylamino, diethylamino, dibenzylamino,phenylamino, diphenylamino, and ditolylamino), an alkoxy group (havingpreferably from 1 to 30 carbon atoms, more preferably from 1 to 20carbon atoms, and especially preferably from 1 to 10 carbon atoms; forexample, methoxy, ethoxy, butoxy, and 2-ethylhexyloxy), an aryloxy group(having preferably from 6 to 30 carbon atoms, more preferably from 6 to20 carbon atoms, and especially preferably from 6 to 12 carbon atoms;for example, phenyloxy, 1-naphthyloxy, and 2-naphthyloxy), aheterocyclic oxy group (having preferably from 1 to 30 carbon atoms,more preferably from 1 to 20 carbon atoms, and especially preferablyfrom 1 to 12 carbon atoms; for example, pyridyloxy, pyrazyloxy,pyrimidyloxy, and quinolyloxy), an acyl group (having preferably from 2to 30 carbon atoms, more preferably from 2 to 20 carbon atoms, andespecially preferably from 2 to 12 carbon atoms; for example, acetyl,benzoyl, formyl, and pivaloyl), an alkoxycarbonyl group (havingpreferably from 2 to 30 carbon atoms, more preferably from 2 to 20carbon atoms, and especially preferably from 2 to 12 carbon atoms; forexample, methoxycarbonyl and ethoxycarbonyl), an aryloxycarbonyl group(having preferably from 7 to 30 carbon atoms, more preferably from 7 to20 carbon atoms, and especially preferably from 7 to 12 carbon atoms;for example, phenyloxycarbonyl), an acyloxy group (having preferablyfrom 2 to 30 carbon atoms, more preferably from 2 to 20 carbon atoms,and especially preferably from 2 to 10 carbon atoms; for example,acetoxy and benzoyloxy), an acylamino group (having preferably from 2 to30 carbon atoms, more preferably from 2 to 20 carbon atoms, andespecially preferably from 2 to 10 carbon atoms; for example,acetylamino and benzoylamino), an alkoxycarbonylamino group (havingpreferably from 2 to 30 carbon atoms, more preferably from 2 to 20carbon atoms, and especially preferably from 2 to 12 carbon atoms; forexample, methoxycarbonylamino), an aryloxycarbonylamino group (havingpreferably from 7 to 30 carbon atoms, more preferably from 7 to 20carbon atoms, and especially preferably from 7 to 12 carbon atoms; forexample, phenyloxycarbonylamino), a sulfonylamino group (havingpreferably from 1 to 30 carbon atoms, more preferably from 1 to 20carbon atoms, and especially preferably from 1 to 12 carbon atoms; forexample, methanesulfonylamino and benzenesulfonylamino), a sulfamoylgroup (having preferably from 0 to 30 carbon atoms, more preferably from0 to 20 carbon atoms, and especially preferably from 0 to 12 carbonatoms; for example, sulfamoyl, methyl sulfamoyl, dimethyl sulfamoyl, andphenyl sulfamoyl), a carbamoyl group (having preferably from 1 to 30carbon atoms, more preferably from 1 to 20 carbon atoms, and especiallypreferably from 1 to 12 carbon atoms; for example, carbamoyl, methylcarbamoyl, diethyl carbamoyl, and phenyl carbamoyl), an alkylthio group(having preferably from 1 to 30 carbon atoms, more preferably from 1 to20 carbon atoms, and especially preferably from 1 to 12 carbon atoms;for example, methylthio and ethylthio), an arylthio group (havingpreferably from 6 to 30 carbon atoms, more preferably from 6 to 20carbon atoms, and especially preferably from 6 to 12 carbon atoms; forexample, phenylthio), a heterocyclic thio group (having preferably from1 to 30 carbon atoms, more preferably from 1 to 20 carbon atoms, andespecially preferably from 1 to 12 carbon atoms; for example,pyridylthio, 2-benzimizolylthio, 2-benzoxazolylthio, and2-benzthiazolylthio), a sulfonyl group (having preferably from 1 to 30carbon atoms, more preferably from 1 to 20 carbon atoms, and especiallypreferably from 1 to 12 carbon atoms; for example, mesyl and tosyl), asulfinyl group (having preferably from 1 to 30 carbon atoms, morepreferably from 1 to 20 carbon atoms, and especially preferably from 1to 12 carbon atoms; for example, methane sulfinyl and benzene sulfinyl),a ureido group (having preferably from 1 to 30 carbon atoms, morepreferably from 1 to 20 carbon atoms, and especially preferably from 1to 12 carbon atoms; for example, ureido, methylureido, andphenylureido), a phosphoramide group (having preferably from 1 to 30carbon atoms, more preferably from 1 to 20 carbon atoms, and especiallypreferably from 1 to 12 carbon atoms; for example, diethylphosphoramideand phenylphosphoramide), a hydroxyl group, a mercapto group, a halogenatom (for example, a fluorine atom, a chlorine atom, a bromine atom, andan iodine atom), a sulfo group, a carboxyl group, a nitro group, ahydroxamic group, a sulfino group, a hydrazino group, an imino group, aheterocyclic group (inclusive of an aromatic heterocyclic group, whichhas preferably from 1 to 30 carbon atoms, and more preferably from 1 to12 carbon atoms and in which examples of the hetero atom include anitrogen atom, an oxygen atom, a sulfur atom, a phosphorus atom, asilicon atom, a selenium atom, and a tellurium atom; and specificexamples thereof include pyridyl, pyrazinyl, pyrimidyl, pyridazinyl,pyrrolyl, pyrazolyl, triazolyl, imidazolyl, oxazolyl, triazolyl,isoxazolyl, isothiazolyl, quinolyl, furyl, thienyl, selenophenyl,tellurophenyl, piperidyl, piperidino, morpholino, pyrrolidyl,pyrrolidino, benzoxazolyl, benzimidazolyl, benzothiazolyl, a carbazolylgroup, an azepinyl group, a silolyl group, a dibenzothiophenyl group,and a dibenzofuranyl group), a silyl group (having preferably from 3 to40 carbon atoms, more preferably from 3 to 30 carbon atoms, andespecially preferably from 3 to 24 carbon atoms; for example,trimethylsilyl and triphenylsilyl), a silyloxy group (having preferablyfrom 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms,and especially preferably from 3 to 24 carbon atoms; for example,trimethylsilyloxy and triphenylsilyloxy), and a phosphoryl group (forexample, a diphenylphosphoryl group and a dimethylphosphoryl group).These substituents may be further substituted, and examples of thefurther substituent include the groups selected from the SubstituentGroup A as described above.

Among the groups of the above-described Substituent Group A, R¹¹ to R¹⁸are each independently preferably a hydrogen atom, an aryl group, or aheteroaryl group, and more preferably a hydrogen atom or an aryl group.

The aryl group represented by R¹¹ to R¹⁸ has preferably from 6 to 30carbon atoms, more preferably from 6 to 20 carbon atoms, and especiallypreferably from 6 to 18 carbon atoms, and examples thereof include aphenyl group, a xylyl group, a biphenyl group, a terphenyl group, anaphthyl group, an anthranyl group, and a triphenylenyl group.

The heteroaryl group represented by R¹¹ to R¹⁸ has preferably the numberof rings of from 5 to 30, more preferably the number of rings of from 5to 20, and especially preferably the number of rings of from 5 to 15,and examples thereof include a pyridyl group, a pyrimidyl group, atriazyl group, a pyrazyl group, a pyridazyl group, a carbazolyl group, adibenzothiophenyl group, and a dibenzofuranyl group.

As described above, R¹¹ to R¹⁸ may further have the substituentrepresented by the Substituent Group A. Examples of the furthersubstituent include an aryl group, a pyridine ring, a pyrimidine ring, atriazine ring, a cyano group, and a carbonyl group.

However, in order to increase the luminous efficiency of greenphosphorescence, it is preferable that the substituents which R¹¹ to R¹⁸may further have are not connected to each other to form a fused ring.In order to increase the luminous efficiency of red phosphorescence, itis also preferable that the substituents which R¹¹ to R¹⁸ may furtherhave are connected to each other to form a fused ring.

Though adjacent two of R¹¹ to R¹⁸ may be bound to each other to form aring, in order to increase the luminous efficiency of greenphosphorescence, it is not preferable that the adjacent two of R¹¹ toR¹⁸ are not bound to each other to forma ring. In order to increase theluminous efficiency of red phosphorescence, it is also preferable thatthe adjacent two of R¹¹ to R¹⁸ are connected to each other to form afused ring.

Preferably, from 5 to 8 of R¹¹ to R¹⁸ are a hydrogen atom, morepreferably, from 6 to 8 of R¹¹ to R¹⁸ are a hydrogen atom, andespecially preferably all of R¹¹ to R¹⁸ are a hydrogen atom.

A¹ to A⁴ each independently represent a nitrogen atom or a carbon atom.Among A¹ to A⁴, the number of carbon atoms is preferably from 2 to 4,more preferably from 3 to 4, and especially preferably 4.

As one of preferred embodiments of the compound represented by thegeneral formula (1), there is exemplified a compound represented by thefollowing general formula (2).

In the general formula (2), R¹ and R² each independently represent ahydrogen atom, a phenyl group, a monovalent oligoaryl group having thenumber of rings of from 2 to 10, or a monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6,provided that at least one of R¹ and R² represents a monovalentoligoaryl group having the number of rings of from 2 to 10 or amonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6, and that the phenyl group, the monovalentoligoaryl group having the number of rings of from 2 to 10, and themonovalent fused polycyclic aromatic hydrocarbon group having the numberof rings of from 2 to 6 do not have an amino group as a substituent; andR¹¹ to R¹⁸ each independently represent a hydrogen atom or asubstituent.

Preferred ranges of R¹ and R² in the general formula (2) are the same asthe preferred ranges of R¹ and R² in the general formula (1).

Preferred ranges of R¹¹ to R¹⁸ in the general formula (2) are the sameas the preferred ranges of R¹¹ to R¹⁸ in the general formula (1).

As one of preferred embodiments of the compound represented by thegeneral formula (1), there is exemplified a compound represented by thefollowing general formula (3).

In the general formula (3), R² represents a hydrogen atom, a phenylgroup, a monovalent oligoaryl group having the number of rings of from 2to 10, or a monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6, and the phenyl group, themonovalent oligoaryl group having the number of rings of from 2 to 10,and the monovalent fused polycyclic aromatic hydrocarbon group havingthe number of rings of from 2 to 6 do not have an amino group as asubstituent; and R¹¹ to R¹⁸, R²¹ to R²⁵, and R³¹ to R³⁵ eachindependently represent a hydrogen atom or a substituent, provided thatR² represents a monovalent oligoaryl group having the number of rings offrom 2 to 10 or a monovalent fused polycyclic aromatic hydrocarbon grouphaving the number of rings of from 2 to 6, at least one of R²¹ to R²⁵and R³¹ to R³⁵ represents an aryl group, or two or more of R²¹ to R²⁵ ortwo or more of R³¹ to R³⁵ are bound to each other to form a fusedpolycyclic aromatic hydrocarbon ring having the number of rings of from2 to 6.

The compound represented by the general formula (3) is more preferablefrom the viewpoint of realizing low voltage because the ionizationpotential is small as compared with the case where R¹ of the generalformula (2) is a hydrogen atom.

Preferred ranges of R¹¹ to R¹⁸ in the general formula (3) are the sameas the preferred ranges of R¹¹ to R¹⁸ in the general formula (1).

Preferred ranges of the phenyl group on which R² and R²¹ to R²⁵ aresubstituted and the phenyl group on which R³¹ to R³⁵ are substituted inthe general formula (3) are the same as the preferred ranges of R¹, R²,and R¹⁹ in the general formula (1).

As one of preferred embodiments of the compound represented by thegeneral formula (1), there is exemplified a compound represented by thefollowing general formula (4).

(In the general formula (4), R¹, R², and R¹⁹ each independentlyrepresent a hydrogen atom, a phenyl group, a monovalent oligoaryl grouphaving the number of rings of from 2 to 10, or a monovalent fusedpolycyclic aromatic hydrocarbon group having the number of rings of from2 to 6, provided that at least one of R¹, R², and R¹⁹ represents a groupselected from the following general formulae (CH-1) to (CH-11), and thatthe phenyl group, the monovalent oligoaryl group having the number ofrings of from 2 to 10, and the monovalent fused polycyclic aromatichydrocarbon group having the number of rings of from 2 to 6 do not havean amino group as a substituent; and R¹¹ to R¹⁸ each independentlyrepresent a hydrogen atom or a substituent.)

(In the general formulae (CH-1) to (CH-11), * represents a bindingsite.)

At least one of R¹, R², and R¹⁹ represents a group selected from thegeneral formulae (CH-1) to (CH-11). In order to increase the luminousefficiency of green phosphorescence, at least one of R¹, R², and R¹⁹ ispreferably a group selected from the general formulae (CH-1) to (CH-8),more preferably a group selected from the general formulae (CH-2) to(CH-8), still more preferably a group selected from the general formulae(CH-3) to (CH-8), and especially preferably a group selected from thegeneral formulae (CH-4) to (CH-8).

In order to increase the luminous efficiency of red phosphorescence, atleast one of R¹, R², and R¹⁹ is preferably a group selected from thegeneral formulae (CH-2) to (CH-11), more preferably a group selectedfrom the general formulae (CH-4) to (CH-11), still more preferably agroup selected from the general formulae (CH-9) to (CH-11), andespecially preferably a group selected from the general formula (CH-9)or (CH-10).

Preferred ranges of R¹¹ to R¹⁸ in the general formula (4) are the sameas the preferred ranges of R¹¹ to R¹⁸ in the general formula (1).

From the viewpoint of deposition adaptability, the molecular weight ofthe compound represented by the general formula (1) is preferably notmore than 800, more preferably 400 or more and not more than 800, stillmore preferably 450 or more and not more than 750, and especiallypreferably 500 or more and not more than 700. What the molecular weightis 450 or more is advantageous for forming an amorphous thin film withgood quality. When the molecular weight is not more than theabove-described upper limit, solubility and sublimation properties areenhanced, and such is advantageous for enhancing the purity of thecompound. Such is also preferable from the viewpoint of laminating acomposition containing the compound represented by the general formula(1) by means of deposition.

In the case of using the compound represented by the general formula (1)as a host material of the light emitting layer of the organicelectroluminescent element or as a charge transporting material of alayer adjacent to the light emitting layer, when an energy gap in athinner film state than the light emitting material as described later(lowest excited triplet (T₁) energy in a thin film state in the casewhere the light emitting material as described later is a phosphorescentmaterial) is large, quenching of the light emission can be preventedfrom occurring, and such is advantageous for enhancing the efficiency.On the other hand, from the viewpoint of chemical stability of thecompound, it is preferable that the energy gap and the T₁ energy are notexcessively large.

The T₁ energy of the compound represented by the general formula (1) ina thin film state is preferably 1.77 eV (40 kcal/mole) or more and notmore than 3.51 eV (81 kcal/mole), and more preferably 2.39 eV (55kcal/mole) or more and not more than 3.25 eV (75 kcal/mole). In theorganic electroluminescent element according to the present invention,from the viewpoint of luminous efficiency, the T₁ energy of the compoundrepresented by the general formula (1) is preferably higher than the T₁energy of the phosphorescent material as described later. In particular,in the case where a luminous color from the organic electroluminescentelement is green (emission peak wavelength: 490 to 580 nm), from theviewpoint of luminous efficiency, the T₁ energy is still more preferably2.39 eV (55 kcal/mole) or more and not more than 2.82 eV (65 kcal/mole).

The T₁ energy can be determined from a short wavelength end obtained bymeasuring a phosphorescent spectrum of a thin film of the material. Forexample, the material is subjected to film forming in a film thicknessof about 50 nm on a rinsed quartz glass substrate by a vacuum depositionmethod, and a phosphorescent spectrum of the thin film is measured usinga Hitachi's fluorescent spectrophotometer F-7000 (manufactured byHitachi High-Technologies Corporation). The T₁ energy can be determinedby reducing a rise-up wavelength on the short wavelength side of theobtained luminous spectrum into an energy unit.

From the viewpoint of stably operating the organic electroluminescentelement against the heat generation at the time of high-temperaturedriving or during the element driving, or the viewpoint of minimizingchromaticity shift at the time of high-temperature storage, in theorganic electroluminescent element according to the present invention,the compound represented by the general formula (1) is preferably acompound having a glass transition temperature of 100° C. or higher. Theglass transition temperature (Tg) of the compound represented by thegeneral formula (1) is more preferably 100° C. or higher and not higherthan 400° C., still more preferably 120° C. or higher and not higherthan 400° C., and especially preferably 140° C. or higher and not higherthan 400° C.

When the purity of the compound represented by the general formula (1)is low, impurities work as a trap of the charge transportation orpromote the deterioration of the element, and therefore, the purity ofthe compound represented by the general formula (1) is preferably ashigh as possible. The purity can be measured by means of, for example,high performance liquid chromatography (HPLC), and when detected at alight absorption intensity at 254 nm, an area ratio of the compoundrepresented by the general formula (1) is preferably 95.0% or more, morepreferably 97.0% or more, especially preferably 99.0% or more, and mostpreferably 99.9% or more. Examples of a method for increasing the purityof the compound represented by the general formula (1) includerecrystallization and sublimation purification.

Specific examples of the compound represented by the general formula (1)are enumerated below, but it should not be construed that the presentinvention is limited thereto.

The compounds exemplified as the compound represented by the generalformula (1) can be synthesized by, for example, a method described inJP-A-2010-087496.

The compound represented by the general formula (1) can also bepreferably synthesized by the following scheme. However, the followingsynthesis scheme is one example of the synthesis, and the compoundrepresented by the general formula (1) can also be synthesized byanother known method.

Concerning the carbazole compounds, synthesis by dehydrogenationaromatization after the Aza-Cope arrangement of the condensation productof an aryl hydrazine and a cyclohexane derivative (L. F. Tieze and Th.Eicher, translated by Takano and Ogasawara, Precision Organic Syntheses,page 339, published by Nanko-Do) is exemplified. In addition, concerningthe coupling reaction of the obtained compound and an aryl halidecompound using a palladium catalyst, the methods described inTetrahedron Letters, Vol. 39, page 617 (1998), ibid., Vol. 39, page 2367(1998), and ibid., Vol. 40, page 6393 (1999) are exemplified. Thereaction temperature and the reaction time are not particularly limited,and the conditions in the above-described documents are applicable. Inaddition, the synthesis can be conducted by the method described in, forexample, WO2007/031165, paragraph 47, et seq.

The compound represented by the general formula (1) is a chargetransporting material for an organic electroluminescent element and maybe contained in any layer other than the light emitting layer in theorganic layer. As for the layer into which the compound represented bythe general formula (1) is introduced, the compound represented by thegeneral formula (1) is preferably contained in any one of the lightemitting layer, a layer between the light emitting layer and a cathode(in particular, a layer adjacent to the light emitting layer), and alayer between the light emitting layer and an anode, more preferablycontained in any one or plural layers of the light emitting layer, anelectron transporting layer, an electron injecting layer, an excitonblocking layer, a hole blocking layer, and an electron blocking layer,still more preferably contained in anyone of the light emitting layer,an electron transporting layer, a hole blocking layer, and a holetransporting layer, and especially preferably contained in the lightemitting layer or an electron transporting layer. In addition, thecompound represented by the general formula (1) may be used in aplurality of the above-described layers. For example, the compoundrepresented by the general formula (1) may be used in both the lightemitting layer and the electron transporting layer.

In the case of containing the compound represented by the generalformula (1) in the light emitting layer, the compound represented by thegeneral formula (1) is contained in an amount of preferably from 0.1 to99% by mass, more preferably from 1 to 97% by mass, and still morepreferably from 10 to 96% by mass relative to the total mass of thelight emitting layer. In the case where the compound represented by thegeneral formula (1) is further contained in the layer other than thelight emitting layer, the compound represented by the general formula(1) is contained in an amount of preferably from 50 to 100% by mass, andmore preferably from 85 to 100% by mass relative to the total mass ofthe layer other than the light emitting layer.

(II) Phosphorescent Material:

In the present invention, the light emitting layer preferably includesat least one phosphorescent material. In the present invention, inaddition to the above-described phosphorescent material, a fluorescentlight emitting material and a phosphorescent material different from thephosphorescent material contained in the light emitting layer can beused as the light emitting material.

Such fluorescent light emitting material and phosphorescent material aredescribed in detail in, for example, paragraphs [0100] to [0164] ofJP-A-2008-270736 and paragraphs [0088] to [0090] of JP-A-2007-266458,the detailed descriptions thereon in these patent documents can beapplied to the present invention.

Examples of the phosphorescent material which can be used in the presentinvention include phosphorescent materials described in patentdocuments, for example, U.S. Pat. No. 6,303,238B1, U.S. Pat. No.6,097,147, WO00/57676, WO00/70655, WO01/08230, WO01/39234A2,WO01/41512A1, WO02/02714A2, WO02/15645A1, WO02/44189A1, WO05/19373A2,JP-A-2001-247859, JP-A-2002-302671, JP-A-2002-117978, JP-A-2003-133074,JP-A-2002-235076, JP-A-2003-123982, JP-A-2002-170684, EP1211257,JP-A-2002-226495, JP-A-2002-234894, JP-A-2001-2475859, JP-A-2001-298470,JP-A-2002-173674, JP-A-2002-203678, JP-A-2002-203679, JP-A-2004-357791,JP-A-2006-256999, JP-A-2007-19462, JP-A-2007-94635, and JP-A-2007-96259.Above all, examples of the light emitting material which is morepreferable include phosphorescent light emitting metal complex compoundssuch as iridium (Ir) complexes, platinum (Pt) complexes, Cu complexes,Re complexes, W complexes, Rh complexes, Ru complexes, Pd complexes, Oscomplexes, Eu complexes, Tb complexes, Gd complexes, Dy complexes, andCe complexes, with iridium (Ir) complexes, platinum (Pt) complexes, andRe complexes being especially preferable. Above all, iridium (Ir)complexes, platinum (Pt) complexes, and Re complexes each including atleast one coordination mode of a metal-carbon bond, a metal-nitrogenbond, a metal-oxygen bond, and a metal-sulfur bond are preferable.Furthermore, from the viewpoints of luminous efficiency, drivingdurability, and chromaticity, iridium (Ir) complexes and platinum (Pt)complexes are especially preferable, and iridium (IR) complexes are themost preferable.

As the phosphorescent material which is contained in the light emittinglayer in the present invention, it is preferable to use an iridium (Ir)complex represented by the following general formula (E-1) or a platinum(Pt) complex as described below.

In the general formula (E-1), Z¹ and Z² each independently represent acarbon atom or a nitrogen atom; A¹ represents an atomic group forforming a 5- or 6-membered heterocyclic ring together with Z¹ and thenitrogen atom; B¹ represents an atomic group for forming a 5- or6-membered heterocyclic ring together with Z² and the carbon atom; (X—Y)represents a monoanionic bidentate ligand; and n_(E1) represents aninteger of from 1 to 3.

Z¹ and Z² are preferably a carbon atom. n_(E1) is preferably 2 or 3. Inthat case, two or three ligands containing Z¹, Z², A¹, and B¹ arepresent, and these ligands may be the same as or different from eachother.

Examples of the 5- or 6-membered heterocyclic ring containing A¹, Z¹,and a nitrogen atom include a pyridine ring, a pyrimidine ring, apyrazine ring, a triazine ring, an imidazole ring, a pyrazole ring, anoxazole ring, a thiazole ring, a triazole ring, an oxadiazole ring, anda thiadiazole ring. The 5- or 6-membered heterocyclic ring formed of A¹,Z¹, and a nitrogen atom may have a substituent.

Examples of the 5- or 6-membered heterocyclic ring formed of B¹, Z², anda carbon atom include a benzene ring, a pyridine ring, a pyrimidinering, a pyrazine ring, a pyridazine ring, a triazine ring, an imidazolering, a pyrazole ring, an oxazole ring, a thiazole ring, a triazolering, an oxadiazole ring, a thiadiazole ring, a thiophene ring, a furanring, and a pyrrole ring. The 5- or 6-membered heterocyclic ring formedof B¹, Z², and a carbon atom may have a substituent.

Examples of the substituent include the groups selected from theSubstituent Group A as described above. The substituents may beconnected to each other to form a ring. Examples of the ring which isformed include an unsaturated 4- to 7-membered ring, a benzene ring, apyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, animidazole ring, an oxazole ring, a thiazole ring, a pyrazole ring, athiophene ring, and a furan ring. Such a formed ring may have asubstituent, and a ring may be further formed via the substituent on theformed ring. In addition, the substituent of the 5- or 6-memberedheterocyclic ring formed of A¹, Z¹, and a nitrogen atom and thesubstituent of the 5- or 6-membered ring formed of B¹, Z², and a carbonatom may be connected to each other to form the same fused ring as thatdescribed above. A ring may be further formed via the substituent on theformed ring.

As the ligand represented by (X—Y), there are enumerated various knownligands which are used in conventionally known metal complexes. Examplesthereof include ligands described in H. Yersin, Photochemistry andPhotophysics of Coordination Compounds, Springer-Verlag, 1987,nitrogen-containing heteroaryl ligands, and diketone ligands. Above all,ligands represented by the following general formulae (1-1) to (1-39)are preferable, and ligands represented by the general formulae (1-1),(1-4), (1-15), (1-16), (1-17), (1-18), (1-19), (1-22), (1-25), (1-28),(1-29), (1-36), and (1-39) are more preferable. However, it should notbe construed that the present invention is limited thereto.

* represents a coordination position to iridium (Ir) in the generalformula (E-1). Rx, Ry, and Rz each independently represent a hydrogenatom or a substituent. Examples of the substituent include thesubstituents selected from the Substituent Group A as described above.Rx and Ry are each independently preferably an alkyl group, aperfluoroalkyl group, or an aryl group. Ry is preferably any one of ahydrogen atom, an alkyl group, a perfluoroalkyl group, a fluorine atom,a cyano group, and an aryl group. Rx and Ry which are plurally presentin one ligand may be the same as or different from each other.

The complex having such a ligand can be synthesized using acorresponding ligand precursor in the same manner as that in knownsynthesis examples.

A preferred embodiment of the iridium (Ir) complex represented by thegeneral formula (E-1) is an iridium (Ir) complex represented by thefollowing general formula (E-2).

In the general formula (E-2), A^(E1) to A^(E8) each independentlyrepresent a nitrogen atom or C—R^(E); and R^(E) represents a hydrogenatom or a substituent. As the substituent, the substituents exemplifiedas the Substituent Group A as described above can be applied. R^(E)s maybe connected to each other to form a ring. Examples of the ring which isformed include the same rings as the fused rings in the general formula(E-1). (X—Y) and n_(E2) are synonymous with (X—Y) and n_(E2) in thegeneral formula (E-1), respectively, and preferred ranges thereof arealso the same. In the case where n_(E2) is 2 or 3, two or three ligandscontaining A^(E1) to A^(E8) are present. In this respect, the ligandsmay be the same as or different from each other.

A more preferred embodiment of the compound represented by the generalformula (E-2) is a compound represented by the following general formula(E-3).

In the general formula (E-3), R^(T1), R^(T2), R^(T3), R^(T4), R^(T5),R^(T6), and R^(T7) are synonymous with R^(E). A represents CR″″ or anitrogen atom, and R″″ is synonymous with R^(E). As for R^(T1) to R^(T7)and R″″, arbitrary two adjacent groups may be bound to each other toform a fused 4- to 7-membered ring; the fused 4- to 7-membered ring is acycloalkene, a cycloalkadiene, an aryl, or an heteroaryl; and the fused4- to 7-membered ring may further have the substituent represented bythe Substituent Group A. (X—Y) and n_(E3) are synonymous with (X—Y) andn_(E1) in the general formula (E-1), respectively, and preferred rangesthereof are also the same. In the case where n_(E3) is 2 or 3, two orthree ligands containing R^(T1), R^(T2), R^(T3), R^(T4), R^(T5), R^(T6),R^(T7), and A are present. In this respect, the ligands may be the sameas or different from each other.

Preferred ranges of A and R^(T1) to R^(T7) vary depending upon theluminous color required according to an application. They are hereunderdescribed while dividing the aimed luminous color into three regions ofa blue to sky blue color, a green to yellow color, and a yellowishorange to red color. However, it should not be construed that thepresent invention is limited thereto.

In order to obtain a luminous color of yellowish orange to red color,the compound represented by the general formula (E-1) is preferably acompound represented by the following general formula (E-4), generalformula (E-5), or general formula (E-6).

In the general formula (E-4), R^(T1) to R^(T4), R^(T7), A (CR″″ or anitrogen atom), (X—Y), and n_(E4) are synonymous with R^(T1) to R^(T4),R^(T7), A, (X—Y), and n_(E3) in the general formula (E-3), respectively.R₁′ to R₄′ are synonymous with R^(E).

As for R^(T1) to R^(T4), R^(T7), R₁′ to R₄′, and R″″, arbitrary twoadjacent groups may be bound to each other to form a fused 4- to7-membered ring; the fused 4- to 7-membered ring is a cycloalkene, acycloalkadiene, an aryl, or an heteroaryl; and the fused 4- to7-membered ring may further have the substituent represented by theSubstituent Group A.

In the case where n_(E4) is 2 or 3, two or three ligands containingR^(T1) to R^(T4), R^(T7), A, and R₁′ to R₄′ are present. In thisrespect, the ligands may be the same as or different from each other.

R₁′ to R₄′ are preferably a hydrogen atom, a fluorine atom, an alkylgroup, or an aryl group. In addition, the case where not only Arepresents CR″″, but from 0 to 3 of R^(T1) to R^(T4), R^(T7), and R″″are an alkyl group or a phenyl group, with all of the remainder being ahydrogen atom, is preferable.

Preferred specific examples of the compound represented by the generalformula (E-4) are enumerated below, but it should not be construed thatthe present invention is limited thereto.

In the general formula (E-5), R^(T2) to R^(T6), A (CR″″ or a nitrogenatom), (X—Y), and n_(E5) are synonymous with R^(T2) to R^(T6), A, (X—Y),and n_(E3) in the general formula (E-3), respectively. R₅′ to R₈′ aresynonymous with R₁′ to R₄′ in the general formula (E-4), respectively.

As for R^(T2) to R^(T6), R₅′ to R₈′, and R″″, arbitrary two adjacentgroups may be bound to each other to form a fused 4- to 7-membered ring;the fused 4- to 7-membered ring is a cycloalkene, a cycloalkadiene, anaryl, or an heteroaryl; and the fused 4- to 7-membered ring may furtherhave the substituent represented by the Substituent Group A.

In the case where n_(E5) is 2 or 3, two or three ligands containingR^(T2) to R^(T6), A, and R₅′ to R₈′ are present. In this respect, theligands may be the same as or different from each other.

In addition, preferred ranges of R₅′ to R₈′ are the same as thepreferred ranges of R₁′ to R₄′ in the general formula (E-4). Inaddition, the case where not only A represents CR″″, but from 0 to 3 ofR^(T2) to R^(T6), R″″, and R₅′ to R₈′ are an alkyl group or a phenylgroup, with all of the remainder being a hydrogen atom, is preferable.

Preferred specific examples of the compound represented by the generalformula (E-5) are enumerated below, but it should not be construed thatthe present invention is limited thereto.

In the general formula (E-6), R^(T1) to R^(T5), A (CR″″ or a nitrogenatom), (X—Y), and n_(E6) are synonymous with R^(T1) to R^(T5), A, (X—Y),and n_(E3) in the general formula (E-3), respectively. R₉′ to R₁₂′ aresynonymous with R₁′ to R₄′ in the general formula (E-4), respectively.

As for R^(T1) to R^(T5), R₉′ to R₁₂′, and R″″, arbitrary two adjacentgroups may be bound to each other to form a fused 4- to 7-membered ring;the fused 4- to 7-membered ring is a cycloalkene, a cycloalkadiene, anaryl, or an heteroaryl; and the fused 4- to 7-membered ring may furtherhave the substituent represented by the Substituent Group A.

In the case where n_(E6) is 2 or 3, two or three ligands containingR^(T1) to R^(T5), A, and R₉′ to R₁₂′ are present. In this respect, theligands may be the same as or different from each other.

In addition, preferred ranges of R₉′ to R₁₂′ are the same as thepreferred ranges of R₁′ to R₄′ in the general formula (E-4). Inaddition, the case where not only A represents CR″″, but from 0 to 3 ofR^(T1) to R^(T5), R″″, and R₉′ to R₁₂′ are an alkyl group or a phenylgroup, with all of the remainder being a hydrogen atom, is preferable.

Preferred specific examples of the compound represented by the generalformula (E-6) are enumerated below, but it should not be construed thatthe present invention is limited thereto.

In order to obtain a luminous color of green to yellow color, thecompound represented by the general formula (E-1) is preferably acompound represented by the following general formula (E-7).

In the general formula (E-7), R^(T1), R^(T2), R^(T3), R^(T4), R^(T5),R^(T6), R^(T7), R″″, (X—Y), and n_(E7) are synonymous with R^(T1),R^(T2), R^(T3), R^(T4), R^(T5), R^(T6), R^(T7), R″″, (X—Y), and n_(E3)in the general formula (E-3), respectively. As for R^(T1) to R^(T7) andR″″, arbitrary two adjacent groups may be bound to each other to form afused 4- to 7-membered ring; the fused 4- to 7-membered ring is acycloalkene, a cycloalkadiene, an aryl, or an heteroaryl; and the fused4- to 7-membered ring may further have the substituent represented bythe Substituent Group A.

In the case where n_(E7) is 2 or 3, two or three ligands containingR^(T1), R^(T2), R^(T3), R^(T4), R^(T5), R^(T6), R^(T7), and R″″ arepresent. In this respect, the ligands may be the same as or differentfrom each other.

R^(T1), R^(T2), R^(T3), R^(T4), R^(T5), R^(T6), R^(T7), and R″″ arepreferably a hydrogen atom, a fluorine atom, an alkyl group, an arylgroup, a heteroaryl group, or a cyano group.

n_(E7) is preferably 3. Furthermore, the compound represented by thegeneral formula (E-7) is preferably a compound represented by thefollowing general formula (E-7-1).

In the general formula (E-7-1), R^(T1), R^(T2), R^(T3), R^(T4), R^(T5),R^(T6), R^(T7), and R″″ are synonymous with R^(T1), R^(T2), R^(T3),R^(T4), R^(T5), R^(T6), R^(T7), and R″″ in the general formula (E-7),respectively, and preferred ranges thereof are also the same. R^(T8) toR^(T15) are synonymous with R^(T1), R^(T2), R^(T3), R^(T4), R^(T5),R^(T6), R^(T7), and R″″, respectively, and preferred ranges thereof arealso the same. The phenylpyridine ligand containing R^(T1), R^(T2),R^(T3), R^(T4), R^(T5), R^(T6), R^(T7), and R″″ and the phenylpyridineligand containing R^(T8) to R^(T15) are different from each other.

In the luminous color of green to yellow color, in order to obtain theluminous color close to a green color, R^(T1), R^(T2), R^(T3), R^(T4),R^(T5), R^(T6), R^(T7), and R″″ are more preferably a hydrogen atom, afluorine atom, an alkyl group, or a cyano group, and from 1 to 3 ofR^(T1), R^(T5), R^(T4), and R″″ are still more preferably an alkylgroup. R^(T8) to R^(T11) are more preferably a hydrogen atom or an alkylgroup. In addition, R^(T12) to R^(T15) are more preferably a hydrogenatom, an alkyl group, a cyano group, or an aryl group. The substitutionposition of the alkyl group, the cyano group, or the aryl group ispreferably R^(T13) or R^(T14). The aryl group may further have asubstituent and may form a fused ring via a substituent.

In the luminous color of green to yellow color, in order to obtain theluminous color close to a yellow color, R^(T1), R^(T2), R^(T3), R^(T4),R^(T5), R^(T6), R^(T7), and R″″ are more preferably a hydrogen atom oran alkyl group, and from 1 to 3 of R^(T1), R^(T5), R^(T4), and R″″ arestill more preferably an alkyl group. At least one of R^(T8) to R^(T11)is more preferably an aryl group, and any one of R^(T9) and R^(T10) isstill more preferably an aryl group, with the remainder being a hydrogenatom or an alkyl group. The aryl group may further have a substituentand may forma fused ring via a substituent.

In the general formula (E-7-1), it is also preferable that the generalformula (E-7-1) includes a partial structure represented by thefollowing general formula (E-7-2). When the partial structurerepresented by the following general formula (E-7-2) is included, theremay be the case where the effects of low voltage and high durability areconspicuously revealed through a combination with the host material.

In the general formula (E-7-2), X is —O—, —S—, —NR^(T24)—,—CR^(T25)R^(T26)—, or —SiR^(T27)R^(T28)—; and any one of R^(T16) toR^(T28) is bound to a part of the general formula (E-7-1) via a singlebond or a substituent.

In the general formula (E-7-2), any one of R^(T16) to R^(T28) ispreferably bound to a part in the general formula (E-7-1) via a singlebond or an aryl group. In the case where it is intended to obtain aluminous color close to a green color, any one of R^(T16) to R^(T28) isbound more preferably at R^(T13) or R^(T14) and still more preferably atR^(T13). In the case where it is intended to obtain a luminous colorclose to a yellow color, any one of R^(T16) to R^(T28) is bound morepreferably at R^(T9) or R^(T10).

X is preferably —O—, —S—, —NR^(T24)—, or —CR^(T25)R^(T26)—, and morepreferably —O— or —S—.

When X is —O— or —S—, the partial structure represented by the generalformula (E-7-2) is preferably bound to a part in the general formula(E-7-1) at the position of R^(T16) via a single bond; when X is—NR^(T24)—, the partial structure represented by the general formula(E-7-2) is preferably bound to a part in the general formula (E-7-1) atthe position of R^(T18) or R^(T24) via a single bond; and when X is—CR^(T25)R^(T26)—, the partial structure represented by the generalformula (E-7-2) is preferably bound to a part in the general formula(E-7-1) at the position of R^(T17) via a single bond.

Preferred specific examples of the compound represented by the generalformula (E-7) are enumerated below, but it should not be construed thatthe present invention is limited thereto.

In order to obtain a luminous color of blue to sky blue color, thecompound represented by the general formula (E-1) is preferably acompound represented by the following general formula (E-8) or generalformula (E-9).

In the general formula (E-8), R^(T1), R^(T2), R^(T3), R^(T4), R^(T5),R^(T6), R^(T7), A (CR″″ or a nitrogen atom), (X—Y), and n_(E8) aresynonymous with R^(T1), R^(T2), R^(T3), R^(T4), R^(T5), R^(T6), R^(T7),A, (X—Y), and n_(E3) in the general formula (E-3), respectively.

In the general formula (E-8), R^(T1) and R^(T5) to R^(T7) are morepreferably a hydrogen atom, an alkyl group, or an aryl group. R^(T2) toR^(T4) are preferably a hydrogen atom, a fluorine atom, or a cyanogroup. A is preferably any one of a fluorine atom or a cyano group interms of R″″ of CR″″, and a nitrogen atom. n_(E8) is preferably 2 or 3.(X—Y) is synonymous with (X—Y) in the general formula (E-1), and apreferred range thereof is also the same.

Preferred specific examples of the compound represented by the generalformula (E-8) are enumerated below, but it should not be construed thatthe present invention is limited thereto.

In the general formula (E-9), R^(T29) to R^(T34), (X—Y), and n_(E9) aresynonymous with R^(T1) to R^(T6), (X—Y), and n_(E3) in the generalformula (E-3), respectively. R^(T35) represents a substituent, andexamples of the substituent include those of the Substituent Group A asdescribed above. As for R^(T29) to R^(T35), arbitrary two adjacentgroups may be bound to each other to forma fused 4- to 7-membered ring;the fused 4- to 7-membered ring is a cycloalkene, a cycloalkadiene, anaryl, or an heteroaryl; and the fused 4- to 7-membered ring may furtherhave the substituent represented by the Substituent Group A.

In the case where n_(E9) is 2 or 3, two or three ligands containingR^(T1), R^(T2), R^(T3), R^(T4), R^(T5), R^(T6), R^(T7), and R″″ arepresent. In this respect, the ligands may be the same as or differentfrom each other.

R^(T29) to R^(T34) are preferably a hydrogen atom, an alkyl group, anaryl group, or a cyano group. R^(T35) is preferably an alkyl group or anaryl group. R^(T35) is preferably connected to R^(T29) to form a ring.It is more preferable that R^(T35) and R^(T29) are bound to each othervia an aryl group, resulting in forming a nitrogen-containing 6-memberedring. As for R^(T35), the aryl group resulting from the connection toR^(T29) may further have a substituent, and from the viewpoint ofdurability, it is still more preferable that the aryl group issubstituted with an alkyl group.

Preferred specific examples of the compound represented by the generalformula (E-9) are enumerated below, but it should not be construed thatthe present invention is limited thereto.

Preferred specific examples of the compound represented by the generalformula (E-1) other than those described above are enumerated below, butit should not be construed that the present invention is limitedthereof.

The compounds exemplified as the compound represented by the generalformula (E-1) can be synthesized by a method described inJP-A-2009-99783 or various methods described in, for example, U.S. Pat.No. 7,278,232. It is preferable that after the synthesis, the product ispurified by means of column chromatography, recrystallization, or thelike and then purified by means of sublimation purification. By thesublimation purification, not only organic impurities can be separated,but inorganic salts, a residual solvent, and the like can be effectivelyremoved.

The compound represented by the general formula (E-1) is preferablycontained in the light emitting layer. However, its application is notlimited, and the compound represented by the general formula (E-1) maybe further contained in any one layer in the organic layers.

The compound represented by the general formula (E-1) in the lightemitting layer is generally contained in an amount of from 0.1% by massto 50% by mass relative to the total mass of the compounds forming thelight emitting layer. From the viewpoints of durability and externalquantum efficiency, the compound represented by the general formula(E-1) is preferably contained in an amount of from 0.2% by mass to 50%by mass, more preferably contained in an amount of from 0.3% by mass to40% by mass, still more preferably contained in an amount of from 0.4%by mass to 30% by mass, and especially preferably contained in an amountof from 0.5% by mass to 20% by mass.

In the present invention, it is especially preferable to use thecompound represented by the general formula (1) in combination of thecompound represented by any one of the general formulae (E-1) to (E-9)in the light emitting layer.

The platinum complex which can be used as the phosphorescent material ispreferably a platinum complex represented by the following generalformula (C-1).

In the general formula (C-1), Q¹, Q², Q³, and Q⁴ each independentlyrepresent a ligand which is coordinated on Pt; and L¹, L², and L³ eachindependently represent a single bond or a divalent connecting group.

The genera formula (C-1) is described. Q¹, Q², Q³, and Q⁴ eachindependently represent a ligand which is coordinated on Pt. At thattime, the bond of each of Q¹, Q², Q³, and Q⁴ to Pt may be any of acovalent bond, an ionic bond, or a coordination bond. As an atom bondingto Pt in each of Q¹, Q², Q³, and Q⁴, a carbon atom, a nitrogen atom, anoxygen atom, a sulfur atom, and a phosphorus atom are preferable. Amongthe atoms bonding to Pt in Q¹, Q², Q³, and Q⁴, it is preferable that atleast one of them is a carbon atom; it is more preferable that two ofthem are a carbon atom; and it is especially preferable that two of themare a carbon atom, with other two being a nitrogen atom.

As Q¹, Q², Q³, and Q⁴ bonding to Pt with a carbon atom, any of ananionic ligand or a neutral ligand is useful. Examples of the anionicligand include a vinyl ligand, an aromatic hydrocarbon ring ligand (forexample, a benzene ligand, a naphthalene ligand, an anthracene ligand, aphenanthrene ligand, etc.) and a heterocyclic ring ligand (for example,a furan ligand, a thiophene ligand, a pyridine ligand, a pyrazineligand, a pyrimidine ligand, a pyridazine ligand, a triazine ligand, atriazole ligand, an oxazole ligand, a pyrrole ligand, an imidazoleligand, a pyrazole ligand, a triazole ligand and condensed ringmaterials including the same (for example, a quinoline ligand, abenzothiazole ligand, etc.), etc.). Examples of the neutral ligandinclude a carbene ligand.

The group represented by each of Q¹, Q², Q³, and Q⁴ may have asubstituent. As the substituent, those exemplified as the SubstituentGroup A as described above can be properly applied. In addition, thesubstituents may be connected to each other (in the case where Q³ and Q⁴are connected to each other, a Pt complex of a cyclic tetradentateligand is formed).

The group represented by Q¹, Q², Q³, and Q⁴ is preferably an aromatichydrocarbon ring ligand bonding to Pt with a carbon atom, an aromaticheterocyclic ring ligand bonding to Pt with a carbon atom, anitrogen-containing aromatic heterocyclic ring ligand bonding to Pt witha nitrogen atom, an acyloxy ligand, an alkyloxy ligand, an aryloxyligand, a heteroaryloxy ligand, or a silyloxy ligand; more preferably anaromatic hydrocarbon ring ligand bonding to Pt with a carbon atom, anaromatic heterocyclic ring ligand bonding to Pt with a carbon atom, anitrogen-containing aromatic heterocyclic ring ligand bonding to Pt witha nitrogen atom, an acyloxy ligand, or an aryloxy ligand; and still morepreferably an aromatic hydrocarbon ring ligand bonding to Pt with acarbon atom, an aromatic heterocyclic ring ligand bonding to Pt with acarbon atom, a nitrogen-containing aromatic heterocyclic ring ligandbonding to Pt with a nitrogen atom, or an acyloxy ligand.

L¹, L², and L³ each represent a single bond or a divalent connectinggroup. Examples of the divalent connecting group represented by L¹, L²,and L³ include an alkylene group (for example, methylene, ethylene,propylene, etc.), an arylene group (for example, phenylene,naphthalenediyl, etc.), a heteroarylene group (for example,pyridinediyl, thiophenediyl, etc.), an imino group (—NR—) (for example,a phenylimino group, etc.), an oxy group (—O—), a thio group (—S—), aphosphinidene group (—PR—) (for example, a phenylphosphinidene group,etc.), a silylene group (—SiRR′—) (for example, a dimethylsilylenegroup, a diphenylsilylene group, etc.), and a combination thereof. Here,examples of R and R′ independently include an alkyl group and an arylgroup. These connecting groups may further have a substituent.

From the viewpoints of stability and light emission quantum yield of thecomplex, L¹, L², and L³ are preferably a single bond, an alkylene group,an arylene group, a heteroarylene group, an imino group, an oxy group, athio group, or a silylene group; more preferably a single bond, analkylene group, an arylene group, or an imino group; still morepreferably a single bond, an alkylene group, or an arylene group; yetstill more preferably a single bond, a methylene group, or a phenylenegroup; even yet still more preferably a single bond or a di-substitutedmethylene group; even yet still more further preferably a single bond, adimethylmethylene group, a diethylmethylene group, a diisobutylmethylenegroup, a dibenzylmethylene group, an ethylmethylmethylene group, amethylpropylmethylene group, an isobutylmethylmethylene group, adiphenylmethylene group, a methylphenylmethylene group, acyclohexanediyl group, a cyclopentanediyl group, a fluorenediyl group,or a fluoromethylmethylene group.

L¹ is especially preferably a dimethylmethylene group, adiphenylmethylene group, or a cyclohexanediyl group, and most preferablya dimethylmethylene group.

L² and L³ are most preferably a single bond.

The platinum complex represented by the general formula (C-1) is morepreferably a platinum complex represented by the following generalformula (C-2).

In the general formula (C-2), L²² represents a single bond or a divalentconnecting group; A²¹ and A²² each independently represent a carbon atomor a nitrogen atom; Z²¹ and Z²² each independently represent anitrogen-containing aromatic heterocyclic ring; and Z²³ and Z²⁴ eachindependently represent a benzene ring or an aromatic heterocyclic ring.

The general formula (C-2) is described. L²¹ is synonymous with L¹ in thegeneral formula (C-1), and a preferred range thereof is also the same.

A²¹ and A²² each independently represent a carbon atom or a nitrogenatom. It is preferable that at least one of A²¹ and A²² is a carbonatom. From the viewpoint of stability of the complex and the viewpointof light emission quantum yield of the complex, it is preferable thatboth A²¹ and A²² are a carbon atom.

Z²¹ and Z²² each independently represent a nitrogen-containing aromaticheterocyclic ring. Examples of the nitrogen-containing aromaticheterocyclic ring represented by Z²² and Z²² include a pyridine ring, apyrimidine ring, a pyrazine ring, a triazine ring, an imidazole ring, apyrazole ring, an oxazole ring, a triazole ring, a triazole ring, anoxadiazole ring, and a thiadiazole ring. From the viewpoints ofstability, control of light emitting wavelength, and light emissionquantum yield of the complex, the ring represented by Z²¹ and Z²² ispreferably a pyridine ring, a pyrazine ring, an imidazole ring, or apyrazole ring, more preferably a pyridine ring, an imidazole ring, or apyrazole ring, still more preferably a pyridine ring or a pyrazole ring,and especially preferably a pyridine ring.

Z²³ and Z²⁴ each independently represent a benzene ring or an aromaticheterocyclic ring. Examples of the nitrogen-containing aromaticheterocyclic ring represented by Z²³ and Z²⁴ include a pyridine ring, apyrimidine ring, a pyrazine ring, a pyridazine ring, a triazine ring, animidazole ring, a pyrazole ring, an oxazole ring, a triazole ring, atriazole ring, an oxadiazole ring, a thiadiazole ring, a thiophene ring,and a furan ring. From the viewpoints of stability, control of lightemitting wavelength, and light emission quantum yield of the complex,the ring represented by Z²³ and Z²⁴ is preferably a benzene ring, apyridine ring, a pyrazine ring, an imidazole ring, a pyrazole ring, or athiophene ring, more preferably a benzene ring, a pyridine ring, or apyrazole ring, and still more preferably a benzene ring or a pyridinering.

Of the platinum complexes represented by the general formula (C-2), oneof more preferred embodiments is a platinum complex represented by thefollowing general formula (C-4).

In the general formula (C-4), A⁴⁰¹ to A⁴¹⁴ each independently representC—R or a nitrogen atom; R represents a hydrogen atom or a substituent;and L⁴¹ represents a single bond or a divalent connecting group.

The general formula (C-4) is described.

A⁴⁰¹ to A⁴¹⁴ each independently represent C—R or a nitrogen atom; and Rrepresents a hydrogen atom or a substituent.

As the substituent represented by R, those exemplified as theSubstituent Group A as described above can be applied.

A⁴⁰¹ to A⁴⁰⁶ are preferably C—R, and Rs may be connected to each otherto form a ring. In the case where A⁴⁰¹ to A⁴⁰⁶ are C—R, R in A⁴⁰² andA⁴⁰⁵ are preferably a hydrogen atom, an alkyl group, an aryl group, anamino group, an alkoxy group, an aryloxy group, a fluorine group, or acyano group, more preferably a hydrogen atom, an amino group, an alkoxygroup, an aryloxy group, or a fluorine group, and especially preferablya hydrogen atom or a fluorine atom. R in A⁴⁰¹, A⁴⁰³, A⁴⁰⁴, and A⁴⁰⁶ ispreferably a hydrogen atom, an alkyl group, an aryl group, an aminogroup, an alkoxy group, an aryloxy group, a fluorine group, or a cyanogroup, more preferably a hydrogen atom, an amino group, an alkoxy group,an aryloxy group, or a fluorine group, and especially preferably ahydrogen atom.

L⁴¹ is synonymous with L¹ in the general formula (C-1), and a preferredrange thereof is also the same.

As A⁴⁰⁷ to A⁴¹⁴, in each of A⁴⁰⁷ to A⁴¹⁰ and A⁴¹¹ to A⁴¹⁴, the number ofN (nitrogen atom) is preferably from 0 to 2, and more preferably from 0to 1. In the case of shifting the light emitting wavelength to the shortwavelength side, it is preferable that any one of A⁴⁰⁸ and A⁴¹² is anitrogen atom; and it is more preferable that both A⁴⁰⁸ and A⁴¹² are anitrogen atom.

Of the platinum complexes represented by the general formula (C-2), oneof more preferred embodiments is a platinum complex represented by thefollowing general formula (C-5).

In the general formula (C-5), A⁵⁰¹ to A⁵¹² each independently representC—R or a nitrogen atom; R represents a hydrogen atom or a substituent;and L⁵¹ represents a single bond or a divalent connecting group.

The general formula (C-5) is described. A⁵⁰¹ to A⁵⁰⁶ and L⁵¹ aresynonymous with A⁴⁰¹ to A⁴⁰⁶ and L⁴¹ in the general formula (C-4),respectively, and preferred ranges thereof are also the same.

A⁵⁰⁷, A⁵⁰⁸ and A⁵⁰⁹, and A⁵¹⁰, A⁵¹¹ and A⁵¹² each independentlyrepresent C—R or a nitrogen atom; and R represents a hydrogen atom or asubstituent. As the substituent represented by R, those exemplified asthe Substituent Group A as described above can be applied.

Of the platinum complexes represented by the general formula (C-1),another more preferred embodiment is a platinum complex represented bythe following general formula (C-6).

In the general formula (C-6), L⁶¹ represents a single bond or a divalentconnecting group; A⁶¹ represents a carbon atom or a nitrogen atom; Z⁶¹and Z⁶² each independently represent a nitrogen-containing aromaticheterocyclic ring; Z⁶³ represents a benzene ring or an aromaticheterocyclic ring; and Y represents an anionic non-cyclic ligand bondingto Pt.

The general formula (C-6) is described. L⁶¹ is synonymous with L¹ in thegeneral formula (C-1), and a preferred range thereof is also the same.

A⁶¹ represents a carbon atom or a nitrogen atom. From the viewpoint ofstability of the complex and the viewpoint of light emission quantumyield of the complex, A⁶¹ is preferably a carbon atom.

Z⁶¹ and Z⁶² are synonymous with Z²¹ and Z²² in the general formula(C-2), respectively, and preferred ranges thereof are also the same. Z⁶³is synonymous with Z²³ in the general formula (C-2), and a preferredrange thereof is also the same.

Y is an anionic non-cyclic ligand bonding to Pt. The non-cyclic ligandas referred to herein is one in which an atom bonding to Pt does notform a ring in a ligand state. The atom bonding to Pt in Y is preferablya carbon atom, a nitrogen atom, an oxygen atom, or a sulfur atom, morepreferably a nitrogen atom or an oxygen atom, and most preferably anoxygen atom.

Examples of Y bonding to Pt with a carbon atom include a vinyl ligand.Examples of Y bonding to Pt with a nitrogen atom include an amino ligandand an imino ligand. Examples of Y bonding to Pt with an oxygen atominclude an alkoxy ligand, an aryloxy ligand, a heteroaryloxy ligand, anacyloxy ligand, a silyloxy ligand, a carboxyl ligand, a phosphateligand, or a sulfonate ligand. Examples of Y bonding to Pt with a sulfuratom include an alkyl mercapto ligand, an aryl mercapto ligand, aheteroaryl mercapto ligand, and a thiocarboxylate ligand.

The ligand represented by Y may have a substituent. As the substituent,those exemplified as the Substituent Group A as described above can beproperly applied. In addition, the substituents may be connected to eachother.

The ligand represented by Y is preferably a ligand bonding to Pt with anoxygen atom, more preferably an acyloxy ligand, an alkyloxy ligand, anaryloxy ligand, a heteroaryloxy ligand, or a silyloxy ligand, and stillmore preferably an acyloxy ligand.

Of the platinum complexes represented by the general formula (C-6), oneof more preferred embodiments is a platinum complex represented by thefollowing general formula (C-7).

In the general formula (C-7), A⁷⁰¹ to A⁷¹⁰ each independently representC—R or a nitrogen atom; R represents a hydrogen atom or a substituent;L⁷¹ represents a single bond or a divalent connecting group; and Yrepresents an anionic non-cyclic ligand bonding to Pt.

The general formula (C-7) is described. L⁷¹ is synonymous with L⁶¹ inthe general formula (C-6), and a preferred range thereof is also thesame. A⁷⁰¹ to A⁷¹⁰ are synonymous with A⁴⁰¹ to A⁴¹⁰ in the generalformula (C-4), respectively, and preferred ranges thereof are also thesame. Y is synonymous with Y in the general formula (C-6), and apreferred range thereof is also the same.

Specific examples of the platinum complex represented by the generalformula (C-1) include compounds disclosed in paragraphs [0143] to[0152], [0157] to [0158], and [0162] to of JP-A-2005-310733, compoundsdisclosed in paragraphs [0065] to [0083] of JP-A-2006-256999, compoundsdisclosed in paragraphs [0065] to [0090] of JP-A-2006-93542, compoundsdisclosed in paragraphs [0063] to [0071] of JP-A-2007-73891, compoundsdisclosed in paragraphs [0079] to [0083] of JP-A-2007-324309, compoundsdisclosed in paragraphs [0065] to [0090] of JP-A-2006-93542, compoundsdisclosed in paragraphs [0055] to [0071] of JP-A-2007-96255, andcompounds disclosed in paragraphs [0043] to [0046] of JP-A-2006-313796.Besides, the following platinum complexes can be exemplified.

The platinum complex compound represented by the general formula (C-1)can be synthesized by various techniques, for example, a methoddescribed at page 789, left-hand column, line 53 to right-hand column,line 7, a method described at page 790, left-hand column lines 18 to 38,a method described page 790, right-hand, lines 19 to 30, and acombination thereof in Journal of Organic Chemistry, 53, 786 (1988), G.R. Newkome, et al.; a method described at page 2752, lines 26 to 35 inChemische Berichte, 113, 2749 (1980), H. Lexy, et al.; and the like.

For example, the platinum complex compound represented by the generalformula (C-1) can be obtained by treating a ligand or a dissociationmaterial thereof and a metal compound in the presence or absence of asolvent (for example, a halogen-based solvent, an alcohol-based solvent,an ether-based solvent, an ester-based solvent, a ketone-based solvent,a nitrile-based solvent, an amide-based solvent, a sulfone-basedsolvent, a sulfoxide-based solvent, water, etc.) and in the presence orabsence of a base (various inorganic or organic bases, for example,sodium methoxide, t-butoxy potassium, triethylamine, potassiumcarbonate, etc.) at room temperature or a lower temperature or byheating (in addition to usual heating, a technique for achieving heatingby microwaves is also effective).

The content of the compound represented by the general formula (C-1) inthe light emitting layer of the present invention is preferably from 1to 30% by mass, more preferably from 3 to 25% by mass, and still morepreferably from 5 to 20% by mass in the light emitting layer.

Such a phosphorescent light emitting metal complex compound ispreferably contained together with the compound represented by thegeneral formula (1) in the light emitting layer.

(III) Other Host Material:

Examples of other host material than the compound represented by thegeneral formula (1), which can be used in the light emitting layer,include compounds having the following partial structure, for example:

Conductive high-molecular oligomers such as aromatic hydrocarbons,pyrrole, indole, carbazole, azaindole, indolocarbazole, azacarbazole,triazole, oxazole, oxadiazole, pyrazole, imidazole, thiophene,polyarylalkanes, pyrazoline, pyrazolone, phenylenediamine, arylamines,amino-substituted chalcone, styrylanthracene, hydrazone, stilbene,silazane, aromatic tertiary amine compounds, styrylamine compounds,porphyrin-based compounds, polysilane-based compounds,poly(N-vinylcarbazole), aniline-based copolymers, thiophene oligomers,and polythiophene, organic silanes, carbon films, pyridine, pyrimidine,triazine, fluorenone, anthraquinodimethane, anthrone, diphenylquinone,thiopyran dioxide, carbodiimide, fluorenylidenemethane,distyrylpyrazine, fluorine-substituted aromatic compounds, heterocyclictetracarboxylic anhydrides such as naphthalene perylene, phthalocyanine,and a variety of metal complexes typified by metal complexes of8-quinolinol derivatives and metal complexes having metalphthalocyanine, benzoxazole, or benzothiazole as a ligand thereof, andderivatives thereof (which may have a substituent or a fused ring).

(Other Layers)

The organic electroluminescent element according to the presentinvention may include layers other than the light emitting layer.

Examples of the organic layer other than the light emitting layer whichmay be included in the organic layer include a hole injecting layer, ahole transporting layer, a blocking layer (e.g., a hole blocking layer,an electron blocking layer, an exciton blocking layer, and the like),and an electron transporting layer. Specifically, examples of the layerconfiguration include those described below, but it should not beconstrued that the present invention is limited to these configurations.

-   -   Anode/hole transporting layer/light emitting layer/electron        transporting layer/cathode    -   Anode/hole transporting layer/light emitting layer/blocking        layer/electron transporting layer/cathode    -   Anode/hole transporting layer/light emitting layer/blocking        layer/electron transporting layer/electron injecting        layer/cathode    -   Anode/hole injecting layer/hole transporting layer/light        emitting layer/blocking layer/electron transporting        layer/cathode    -   Anode/hole injecting layer/hole transporting layer/light        emitting layer/electron transporting layer/electron injecting        layer/cathode    -   Anode/hole injecting layer/hole transporting layer/light        emitting layer/blocking layer/electron transporting        layer/electron injecting layer/cathode    -   Anode/hole injecting layer/hole transporting layer/blocking        layer/light emitting layer/blocking layer/electron transporting        layer/electron injecting layer/cathode

The organic electroluminescent element according to the presentinvention preferably includes at least one organic layer which ispreferably disposed between the (A) anode and the light emitting layer.Examples of the organic layer which is preferably disposed between the(A) anode and the light emitting layer include an hole injecting layer,a hole transporting layer, and an electron blocking layer from the anodeside.

The organic electroluminescent element according to the presentinvention preferably includes at least one organic layer which ispreferably disposed between the (B) cathode and the light emittinglayer. Examples of the organic layer which is preferably disposedbetween the (B) cathode and the light emitting layer include an electroninjecting layer, an electron transporting layer, and a hole blockinglayer from the cathode side.

Specifically, an example of the preferred embodiments of the organicelectroluminescent element according to the present invention is theembodiment shown in FIG. 1, in which a hole injecting layer 4, a holetransporting layer 5, a light emitting layer 6, a hole blocking layer 7,and an electron transporting layer 8 are laminated in this order as theorganic layer from the anode 3 side.

These layers other than the light emitting layer which the organicelectroluminescent element according to the present invention may haveare hereunder described.

(A) Organic Layer Preferably Disposed Between Anode and Light EmittingLayer:

First, (A) the organic layer preferably disposed between the anode andthe light emitting layer is described.

(A-1) Hole Injecting Layer and Hole Transporting Layer

Each of the hole injecting layer and the hole transporting layer is alayer having a function of accepting holes from the anode or the anodeside to transport them into the cathode side. A hole injecting materialand a hole transporting material used in these layers may be any of alow-molecular compound or a high-molecular compound.

With respect to the hole injecting layer and the hole transporting, thedetailed descriptions in paragraphs [0165] to [0167] of JP-A-2008-270736can be applied to the present invention.

In the organic electroluminescent element according to the presentinvention, each of the following compounds is preferably contained inthe organic layer between the light emitting layer and the anode, andmore preferably contained in the hole injecting layer.

Specifically, compounds having the following structures are preferable.

In the organic electroluminescent element according to the presentinvention, at least one of compounds represented by the followinggeneral formula (HT-1) is preferably contained in the organic layerbetween the light emitting layer and the anode, and more preferablycontained in the hole transporting layer.

Examples of the hole transporting material include triarylaminecompounds represented by the following general formula (HT-1).

In the general formula (HT-1), R^(A1) to R^(A15) each represent ahydrogen atom or a substituent.

Examples of the substituent represented by R^(A1) to R^(A15) include thesubstituents exemplified as the Substituent Group A. The adjacentsubstituents may be bounded to each other via a single bond or aconnecting group. From the viewpoints of heat resistance and durability,at least one of R^(A1) to R^(A5) and at least one of R^(A6) to R^(A10)are preferably an aryl group.

Specific examples of the compound represented by the general formula(HT-1) are shown below, but it should not be construed that the presentinvention is limited thereto.

In the case of using the compound represented by the general formula(HT-1) in the hole transporting layer, the compound represented by thegeneral formula (HT-1) is contained in an amount of preferably from 50to 100% by mass, more preferably from 80 to 100% by mass, and especiallypreferably from 95 to 100% by mass.

In addition, in the case of using the compound represented by thegeneral formula (HT-1) in plural organic layers, it is preferable thatthe compound represented by the general formula (HT-1) is contained inan amount falling within the foregoing range in each of the layers.

Only one kind of the compound represented by the general formula (HT-1)may be contained, or a plurality of the compounds represented by thegeneral formula (HT-1) may be contained in an arbitrary combination, inany one of the organic layers.

The thickness of the hole transporting layer containing the compoundrepresented by the general formula (HT-1) is preferably from 1 nm to 500nm, more preferably from 3 nm to 200 nm, and still more preferably from5 nm to 100 nm. In addition, the hole transporting layer is preferablyprovided in a contact state with the light emitting layer.

The hole transporting layer may have either a single layer structurecomposed of one or two or more kinds of the above-described materials ormay be of a multilayer structure composed of a plurality of layers ofthe same composition or different compositions.

The lowest excited triplet (T₁) energy of the compound represented bythe general formula (HT-1) in a thin film state is preferably 2.52 eV(58 kcal/moles) or more and not more than 3.47 eV (80 kcal/mole), morepreferably eV (57 kcal/moles) or more and not more than 3.25 eV (75kcal/mole), and still more preferably 2.52 eV (58 kcal/moles) or moreand not more than 3.04 eV (70 kcal/mole).

The hydrogen atom constituting the general formula (HT-1) also includesisotopes (a deuterium atom and the like). In that case, all of thehydrogen atoms in the compound may be substituted with a hydrogenisotope, or a part thereof may be a mixture of a compound containing ahydrogen isotope.

The compound represented by the general formula (HT-1) can besynthesized by a combination of various known synthesis methods. Mostgenerally, concerning the carbazole compounds, synthesis bydehydrogenation aromatization after the Aza-Cope arrangement of thecondensation product of an aryl hydrazine and a cyclohexane derivative(L. F. Tieze and Th. Eicher, translated by Takano and Ogasawara,Precision Organic Syntheses, page 339, published by Nanko-Do) isexemplified. In addition, concerning the coupling reaction of theobtained compound and an aryl halide compound using a palladiumcatalyst, the methods described in Tetrahedron Letters, Vol. 39, page617 (1998), ibid., Vol. 39, page 2367 (1998), and ibid., Vol. 40, page6393 (1999) are exemplified. The reaction temperature and the reactiontime are not particularly limited, and the conditions in theabove-described documents are applicable.

As for the compound represented by the general formula (HT-1) in thepresent invention, though it is preferable to forma thin layer by avacuum deposition process, a wet process such as solution coating canalso be suitably adopted. From the viewpoints of deposition adaptabilityand solubility, the molecular weight of the compound is preferably notmore than 2,000, more preferably not more than 1,200, and especiallypreferably not more than 800. In addition, from the viewpoint ofdeposition adaptability, when the molecular weight is too low, the vaporpressure becomes low, and a change from the vapor phase to the solidphase does not occur, so that it becomes difficult to form the organiclayer. Thus, the molecular weight of the compound is preferably 250 ormore, and especially preferably 300 or more.

(A-2) Electron Blocking Layer:

The electron blocking layer is a layer having a function of preventingthe electrons, which have been transported from the cathode side to thelight emitting layer, from passing through to the anode side. In thepresent invention, the electron blocking layer can be provided as anorganic layer adjacent to the light emitting layer on the anode side.

As the organic compound constituting the electron blocking layer, forexample, those exemplified above as the hole transporting material canbe used.

The thickness of the electron blocking layer is preferably from 1 nm to500 nm, more preferably from 3 nm to 200 nm, and still more preferablyfrom 5 nm to 100 nm.

The electron blocking layer may have either a single layer structurecomposed of one or two or more kinds of materials selected from theabove-exemplified materials or a multilayer structure composed of aplurality of layers having the same composition or differentcompositions.

In order to prevent the energy movement of excitons produced in thelight emitting layer and not lower the luminous efficiency, the T₁energy of the organic compound constituting the electron blocking layerin a film state is preferably higher than the T₁ energy of the lightemitting material is preferable.

(B) Organic Layer Preferably Disposed Between Cathode and Light EmittingLayer:

Next, the (B) organic layer preferably disposed between the cathode andthe light emitting layer is described.

(B-1) Electron Injecting Layer and Electron Transporting Layer:

The electron injecting layer and the electron transporting layer are alayer having a function of receiving electrons from the cathode or thecathode side and transporting them to the anode side. The electroninjecting material and the electron transporting material used in theselayers may be either a low-molecular compound or a high-molecularcompound.

As the electron transporting material, for example, the compoundrepresented by the general formula (1) can be used. As other electrontransporting materials, anyone of compounds selected from aromatic ringtetracarboxylic acid anhydrides such as pyridine derivatives, quinolinederivatives, pyrimidine derivatives, pyrazine derivatives, phthalazinederivatives, phenanthroline derivatives, triazine derivatives, triazolederivatives, oxazole derivatives, oxadiazole derivatives, imidazolederivatives, benzimidazole derivatives, imidazopyridine derivatives,fluorenone derivatives, anthraquinodimethane derivatives, anthronederivatives, diphenylquinone derivatives, thiopyranedioxide derivatives,carbodiimide derivatives, fluorenylidenemethane derivatives,distyrylpyrazine derivatives, naphthalene, and perylene; various metalcomplexes typified by metal complexes of phthalocyanine derivatives or8-quinolinol derivatives and metal complexes having metalphthalocyanine, benzoxazole, or benzothiazole as a ligand thereof,organic silane derivatives typified by silole; hydrocarbon compoundswith fused rings, such as naphthalene, anthracene, phenanthrene,triphenylene, and pyrene is preferable. Any one of compounds selectedfrom pyridine derivatives, benzimidazole derivatives, imidazopyridinederivatives, metal complexes, and hydrocarbon compounds with fused ringsare more preferable.

From the viewpoint of decreasing the driving voltage, the thickness ofeach of the electron injecting layer and the electron transporting layeris preferably not more than 500 nm.

The thickness of the electron transporting layer is preferably from 1 nmto 500 nm, more preferably from 5 nm to 200 nm, and still morepreferably from 10 nm to 100 nm. In addition, the thickness of theelectron injecting layer is preferably from 0.1 nm to 200 nm, morepreferably from 0.2 nm to 100 nm, and still more preferably from 0.5 nmto 50 nm.

The electron injecting layer and the electron transporting layer mayhave either a single layer structure composed of one or two or morekinds of the above-described materials selected or a multilayerstructure composed of a plurality of layers having the same compositionor different compositions.

The electron injecting layer can contains an electron donating dopant.By incorporating the electron donating dopant into the electroninjecting layer, for example, there are brought such effects that theelectron injecting properties are enhanced; that the driving voltage islowered; and that the efficiency is enhanced. The electron donatingdopant may be any one of organic materials and inorganic materials aslong as it is capable of giving electrons to the material to be dopedand generating radical anions. Examples thereof include dihydroimidazolecompounds such as tetrathiafulvalene (TTF), tetrathianaphthacene (TTT),and bis-[1, 3-diethyl-2-methyl-1, 2-dihydrobenzimidazolyl], lithium, andcesium.

The electron donating dopant in the electron injecting layer iscontained in the amount of preferably from 0.01% by mass to 50% by mass,more preferably from 0.1% by mass to 40% by mass, and still morepreferably 0.5% by mass to 30% by mass relative to the total mass of thecompounds forming the electron injecting layer.

(B-2) Hole Blocking Layer:

The hole blocking layer is a layer having a function of preventingholes, which have been transported from the anode side to the lightemitting layer, from passing through to the cathode side. In the presentinvention, the hole blocking layer can be provided as an organic layeradjacent to the light emitting layer on the cathode side.

In order to prevent the energy movement of excitons produced in thelight emitting layer and not lower the luminous efficiency, the T₁energy of the organic compound constituting the hole blocking layer in afilm state is preferably higher than the T₁ energy of the light emittingmaterial is preferable.

As an example of the organic compound constituting the hole blockinglayer, for example, the compound represented by the general formula (1)can be used.

Examples of the organic compounds constituting the hole blocking layer,other than the compound represented by the general formula (1), includealuminum complexes such as aluminum(III) tris-8-dydroxyquinoline(abbreviated as “Alq”), aluminum(III) bis(2-methyl-8-quinolinato)4-phenylphenolate (abbreviated as “BAlq”), triazole derivatives, andphenanthroline derivatives such as 2, 9-dimethyl-4, 7-diphenyl-1,10-phenanthroline (abbreviated as “BCP”). In the present invention, thehole blocking layer is not limited to the function to actually blockholes, and it may have a function to not diffuse the excitons of thelight emitting layer into the electron transporting layer, or to blockthe energy movement extinction. The compound represented by the generalformula (1) can also be applied to the hole blocking layer.

The thickness of the hole blocking layer is preferably from 1 nm to 500nm, more preferably from 3 nm to 100 nm, and still more preferably from5 nm to 50 nm.

The hole blocking layer may have either a single layer structurecomposed of one or two or more kinds of the above-described materials ora multilayer structure composed of a plurality of layers having the samecomposition or different compositions.

The material which is used in the hole blocking layer preferably hashigher T₁ energy than that of the light emitting material in view ofcolor purity, luminous efficiency, and driving durability.

(B-3) Material Especially Preferably Used in Organic Layer, which isPreferably Disposed Between Cathode and Light Emitting Layer:

For the organic electroluminescent element according to the presentinvention, examples of the material which is especially preferably usedin the materials for an organic layer, preferably disposed between the(B) cathode and the light emitting layer include the compoundrepresented by the general formula (1) and an aromatic hydrocarboncompound (in particular, compounds represented by the following generalformula (Tp-1) and the following general formula (O-1).

The aromatic hydrocarbon compound and the compound represented by thegeneral formula (O-1) are hereunder described.

[Aromatic Hydrocarbon Compound]

The aromatic hydrocarbon compound is more preferably contained in theorganic layer which is located between the light emitting layer and thecathode and adjacent to the light emitting layer. However, the aromatichydrocarbon compound is not limited with respect to an applicationthereof and may further be contained in any layer in the organic layers.As for the layer into which the aromatic hydrocarbon compound isintroduced, the aromatic hydrocarbon compound can be contained in anyone or plural layers of the light emitting layer, the hole injectinglayer, the hole transporting layer, the electron transporting layer, theelectron injecting layer, the exciton blocking layer, and the chargeblocking layer.

The organic layer in which the aromatic hydrocarbon compound iscontained, and which is located between the light emitting layer and thecathode and adjacent to the light emitting layer, is preferably theblocking layer (the hole blocking layer or the exciton blocking layer)or the electron transporting layer, and more preferably the electrontransporting layer.

In the case of containing the aromatic hydrocarbon compound in otherlayer than the light emitting layer, it is contained in an amount ofpreferably from 70 to 100% by mass, and more preferably from 85 to 100%by mass. In the case of containing the aromatic hydrocarbon compound inthe light emitting layer, it is contained in an amount of preferablyfrom 0.1 to 99% by mass, more preferably from 1 to 95% by mass, andstill more preferably from 10 to 95% by mass relative to the total massof the light emitting layer.

As the aromatic hydrocarbon compound, it is preferable to use ahydrocarbon compound having a molecular weight falling within the rangeof from 400 to 1,200 and having a fused polycyclic skeleton having from13 to 22 carbon atoms in total. The fused polycyclic skeleton havingfrom 13 to 22 carbon atoms in total is preferably any one of fluorene,anthracene, phenanthrene, tetracene, chrysene, pentacene, pyrene,perylene, and triphenylene. From the viewpoint of T₁, fluorene,triphenylene, and phenanthrene are more preferable, and from theviewpoints of stability and charge injecting or transporting propertiesof the compound, the compound represented by the following generalformula (Tp-1) is especially preferable.

The aromatic hydrocarbon compound represented by the general formula(Tp-1) has a molecular weight in the range of preferably from 400 to 1,200, more preferably from 400 to 1, 100, and still more preferably from400 to 1,000. So far as the molecular weight is 400 or more, anamorphous thin film with good quality can be formed, whereas what themolecular weight is not more than 1,200 is preferable in view ofsolubility in a solvent and sublimation and deposition adaptabilities.

The aromatic hydrocarbon compound represented by the general formula(Tp-1) is not limited with respect to an application thereof and may becontained in not only the organic layer adjacent to the light emittinglayer but any layer in the organic layers.

In the general formula (Tp-1), R¹² to R²³ each independently represent ahydrogen atom, an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group (each of which may be furthersubstituted with an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group). However, all of R¹² to R²³are not a hydrogen atom at the same time.

Examples of the alkyl group represented by R¹² to R²³ includesubstituted or unsubstituted alkyl groups such as a methyl group, anethyl group, an isopropyl group, an n-butyl group, a tert-butyl group,an n-octyl group, an n-decyl group, an n-hexadecyl group, a cyclopropylgroup, a cyclopentyl group, and a cyclohexyl group. Of these, a methylgroup, an ethyl group, an isopropyl group, a tert-butyl group, and acyclohexyl group are preferable, and a methyl group, an ethyl group, anda tert-butyl group are more preferable.

R¹² to R²³ are preferably an alkyl group having from 1 to 4 carbonatoms, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group (each of which may be further substituted with analkyl group, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group), and more preferably a phenyl group, a fluorenylgroup, a naphthyl group, or a triphenylenyl group.

R¹² to R²³ are especially preferably a benzene ring which may besubstituted with a phenyl group, a fluorenyl group, a naphthyl group, ora triphenylenyl group (each of which may be further substituted with analkyl group, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group).

The total number of the aryl rings in the general formula (Tp-1) ispreferably from 2 to 8, and more preferably from 3 to 5. When the totalnumber of the aryl rings in the general formula (Tp-1) is allowed tofall within this range, an amorphous thin film with good quality can beformed, and the solubility in a solvent and the sublimation anddeposition adaptabilities become good.

R¹² to R²³ each independently have the total carbon number of preferablyfrom 20 to 50, and more preferably from 20 to 36. When the total carbonnumber is allowed to fall within this range, an amorphous thin film withgood quality can be formed, and the solubility in a solvent and thesublimation and deposition adaptabilities become good.

The hydrocarbon compound represented by the general formula (Tp-1) isalso preferably a compound represented by the following general formula(Tp-3).

In the general formula (Tp-3), L represents an n-valent connecting groupcomposed of an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group (each of which may be furthersubstituted with an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group), or a combination thereof. nrepresents an integer of from 2 to 6.

The alkyl group, the phenyl group, the fluorenyl group, the naphthylgroup, and the triphenylenyl group, each of which forms the n-valentconnecting group represented by L, are synonymous with those exemplifiedfor R¹² to R²³.

L is preferably an n-valent connecting group composed of an alkyl group,or a benzene ring or a fluorene ring, each of which may be substitutedwith a benzene ring, or a combination thereof.

Preferred specific examples of L are enumerated below, but it should notbe construed that the present invention is limited thereto.

n is preferably from 2 to 5, and more preferably from 2 to 4.

The compound represented by the general formula (Tp-1) is preferably acompound represented by the following general formula (Tp-4).

In the general formula (Tp-4), A^(A1) to A^(A12) each independentlyrepresent CR⁴⁰⁰ or a nitrogen atom; and n⁴⁰¹ represents an integer offrom 0 to 8. In the case where n⁴⁰¹ is 0, the ring represented by A^(A1)to A^(A6) represents a single bond between the triphenylene ring and thering represented by A^(A7) to A^(A12). In the case where n⁴⁰¹ is from 2to 6, plurally existing rings represented by A^(A1) to A^(A6) may varyat every appearance, and a connecting mode between plurally existingrings to each other may vary at every appearance.

Incidentally, in the present invention, the hydrogen atom in thedescription of the general formula (Tp-4) also includes isotopes (adeuterium atom and the like), and the atoms constituting the substituentare also intended to include isotopes of the atoms.

In the general formula (Tp-4), R⁴¹¹ to R⁴²¹ each independently representa hydrogen atom, an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group (each of which may be furthersubstituted with an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group).

R⁴¹¹ to R⁴²¹ are preferably a hydrogen atom, an alkyl group having from1 to 4 carbon atoms, a phenyl group, a fluorenyl group, a naphthylgroup, or a triphenylenyl group (each of which may be furthersubstituted with an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group), more preferably a hydrogenatom or a phenyl group (the phenyl group may be substituted with analkyl group, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group), and especially preferably a hydrogen atom.

A^(A1) to A^(A12) are preferably CR⁴⁰⁰.

In the general formula (Tp-4), the substituent represented by R⁴⁰⁰represents a hydrogen atom, an alkyl group having from 1 to 4 carbonatoms, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group (each of which may be further substituted with analkyl group, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group). Plurally existing R⁴⁰⁰ s may be different fromeach other.

R⁴⁰⁰ is preferably a hydrogen atom, an alkyl group having from 1 to 4carbon atoms, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group (each of which may be further substituted with analkyl group, a phenyl group, a fluorenyl group, a naphthyl group, or atriphenylenyl group), more preferably a hydrogen atom, an alkyl grouphaving from 1 to 4 carbon atoms, or a phenyl group (each of which may besubstituted with an alkyl group, a phenyl group, a fluorenyl group, anaphthyl group, or a triphenylenyl group), and especially preferably ahydrogen atom, an alkyl group having from 1 to 4 carbon atoms, or aphenyl group (each of which may be substituted with an alkyl group, aphenyl group, a fluorenyl group, a naphthyl group, or a triphenylenylgroup).

n⁴⁰¹ is preferably an integer of from 0 to 5, more preferably an integerof from 1 to 5, and especially preferably an integer of from 2 to 4.

In the case where n⁴⁰¹ is an integer of 1 or more, and the connectingposition to the ring represented by A^(A7) to A^(A12) is A^(A3), fromthe viewpoint of luminous efficiency, the substituent represented byA^(A4) or A^(A5) is CR⁴⁰⁰, and R⁴⁰⁰ is preferably an alkyl group havingfrom 1 to 4 carbon atoms or a phenyl group, more preferably an alkylgroup having from 1 to 4 carbon atoms, and especially preferably amethyl group.

In the general formula (Tp-4), among the respective 6-membered aromaticrings constituted of A^(A1) to A^(A12), the number of rings containing anitrogen atom is preferably not more than 1, and more preferably 0. Inthe general formula (Tp-4), though the connection of the respective6-membered aromatic rings constituted of A^(A1) to A^(A12) is notlimited, the connection at the meta-position or para-position ispreferable. Furthermore, in the compound represented by the generalformula (Tp-4), the number of aromatic rings continuously connecting atthe para-position to each other including a phenyl ring that is apartial structure of the fused ring constituting the triphenylene ringis preferably not more than 3.

In the case of using the hydrocarbon compound represented by the generalformula (Tp-1) in the host material of the light emitting layer of theorganic electroluminescent element or the charge transporting materialof the layer adjacent to the light emitting layer, when an energy gap ina thinner film state than the light emitting material (lowest excitedtriplet (T₁) energy in a thin film state in the case where the lightemitting material as described later is a phosphorescent material) islarge, quenching of the light emission can be prevented from occurring,and such is advantageous for enhancing the efficiency. On the otherhand, from the viewpoint of chemical stability of the compound, it ispreferable that the energy gap and the T₁ energy are not excessivelylarge. The T₁ energy of the compound represented by the general formula(Tp-1) in a thin film state is preferably 1.77 eV (40 kcal/moles) ormore and not more than 3.51 eV (81 kcal/mole), and more preferably 2.39eV (55 kcal/moles) or more and not more than 3.25 eV (75 kcal/mole).From the viewpoint of luminous efficiency, it is preferable that in theorganic electroluminescent element according to the present invention,the T₁ energy of the compound represented by the general formula (Tp-1)is higher than the T₁ energy of the phosphorescent material. Inparticular, in the case where a luminous color from the organicelectroluminescent element is green (emission peak wavelength: 490 to580 nm), from the viewpoint of luminous efficiency, the T₁ energy isstill more preferably 2.39 eV (55 kcal/mole) or more and not more than2.82 eV (65 kcal/mole).

The T₁ energy of the hydrocarbon compound represented by the generalformula (Tp-1) can be determined by the same method as that in thedescription of the general formula (1).

From the viewpoint of stably operating the organic electroluminescentelement against the heat generation at the time of high-temperaturedriving or during the element driving, the glass transition temperature(Tg) of the hydrocarbon compound according to the present invention ispreferably 80° C. or higher and not higher than 400° C., more preferably100° C. or higher and not higher than 400° C., and still more preferably120° C. or higher and not higher than 400° C.

Specific examples of the hydrocarbon compound represented by the generalformula (Tp-1) are exemplified below, but it should not be construedthat the hydrocarbon compound used in the present invention is limitedthereto.

The compounds exemplified as the hydrocarbon compound represented by thegeneral formula (Tp-1) can be synthesized by methods described inWO05/013388, WO06/130598, WO09/021107, US2009/0009065, WO09/008311, andWO04/018587.

It is preferable that after the synthesis, the product is purified bymeans of column chromatography, recrystallization, or the like and thenpurified by means of sublimation purification. By the sublimationpurification, not only organic impurities can be separated, butinorganic salts, a residual solvent, and the like can be effectivelyremoved.

[Compound Represented by the General Formula (O-1)]

From the viewpoints of efficiency and driving voltage of the organicelectroluminescent element, it is preferable to use a compoundrepresented by the following general formula (O-1) as a material whichis especially preferably used for the material of the organic materialpreferably disposed between the (B) cathode and the light emittingmaterial. The general formula (O-1) is hereunder described.

In the general formula (O-1), R^(O1) represents an alkyl group, an arylgroup, or a heteroaryl group. A^(O1) to A^(O4) each independentlyrepresent C—R^(A) or a nitrogen atom. R^(A) represents a hydrogen atom,an alkyl group, an aryl group, or a heteroaryl group, and plural R^(A)smay be the same as or different from each other. L^(O1) represents anyof divalent to hexavalent linking groups composed of an aryl ring or aheteroaryl ring. n^(O1) represents an integer of 2 to 6.

In the general formula (O-1), R^(O1) represents an alkyl group, an arylgroup, or a heteroaryl group. A^(O1) to A^(O4) each independentlyrepresent C—R^(A) or a nitrogen atom. R^(A) represents a hydrogen atom,an alkyl group, an aryl group, or a heteroaryl group, and plural R^(A)smay be the same as or different from each other. L^(O1) represents anyof divalent to hexavalent linking groups composed of an aryl ring or aheteroaryl ring. n^(O1) represents an integer of 2 to 6.

R^(O1) represents an alkyl group (preferably having from 1 to 8 carbonatoms), an aryl group (preferably having from 6 to 30 carbon atoms), ora heteroaryl group (preferably having from 4 to 12 carbon atoms), whichmay have a substituent selected from the above-described SubstituentGroup A. R^(O1) is preferably an aryl group or a heteroaryl group, andmore preferably an aryl group. Preferred examples of the substituent inthe case where the aryl group of R^(O1) has a substituent include analkyl group, an aryl group, and a cyano group. Of these, an alkyl groupand an aryl group are more preferable, with an aryl group being stillmore preferable. In the case where the aryl group of R^(O1) has pluralsubstituents, the plural substituents may be bonded to each other toform a 5- or 6-membered ring. The aryl group of R^(O1) is preferably aphenyl group which may have a substituent selected from the SubstituentGroup A, more preferably a phenyl group which may be substituted with analkyl group or an aryl group, and still more preferably an unsubstitutedphenyl group or a 2-phenylphenyl group.

A^(O1) to A^(O4) each independently represent C—R^(A) or a nitrogenatom. It is preferable that from 0 to 2 of A^(O1) to A^(O4) are anitrogen atom; and it is more preferable that 0 or 1 of A^(O1) to A^(O4)is a nitrogen atom. It is preferable that all of A^(O1) to A^(O4) areC—R^(A), or A^(O1) is a nitrogen atom, and A^(O2) to A^(O4) are C—R^(A);it is more preferable that A^(O1) is a nitrogen atom, and A^(O2) toA^(O4) are C—R^(A); and it is still more preferable that A^(O1) is anitrogen atom, A^(O2) to A^(O4) are C—R^(A), and R^(A)s are all ahydrogen atom.

R^(A) represents a hydrogen atom, an alkyl group (preferably having from1 to 8 carbon atoms), an aryl group (preferably having from 6 to 30carbon atoms), or a heteroaryl group (preferably having from 4 to 12carbon atoms), and may have a substituent selected from theabove-described Substituent Group A. In addition, plural R^(A)s may bethe same as or different from each other. R^(A) is preferably a hydrogenatom or an alkyl group, and more preferably a hydrogen atom.

L^(O1) represents a divalent to hexavalent linking group composed of anaryl ring (preferably having from 6 to 30 carbon atoms) or a heteroarylring (preferably having from 4 to 12 carbon atoms). L^(O1) is preferablyan arylene group, a heteroarylene group, an aryltriyl group, or aheteroaryltriyl group, more preferably a phenylene group, a biphenylenegroup, or a benzenetriyl group, and still more preferably a biphenylenegroup or a benzenetriyl group. L^(O1) may have a substituent selectedfrom the above-described Substituent Group A, and in the case where L⁰¹has a substituent, the substituent is preferably an alkyl group, an arylgroup, or a cyano group. Specific examples of L^(O1) include thefollowing.

n^(O1) represents an integer of from 2 to 6, preferably an integer offrom 2 to 4, and more preferably 2 or 3. n^(O1) is most preferably 3from the viewpoint of efficiency of the organic electroluminescentelement, or n^(O1) is most preferably 2 from the viewpoint of durabilityof the organic electroluminescent element.

The compound represented by the general formula (O-1) is more preferablya compound represented by the following general formula (O-2).

In the general formula (O-2), R^(O1) represents an alkyl group, an arylgroup, or a heteroaryl group. R⁰² to R⁰⁴ each independently represents ahydrogen atom, an alkyl group, an aryl group, or a heteroaryl group.A^(O1) to A^(O4) each independently represent C—R^(A) or a nitrogenatom. R^(A) represents a hydrogen atom, an alkyl group, an aryl group,or a heteroaryl group, and plural R^(A)s may be the same as or differentfrom each other.

R⁰¹ and A^(O1) to A^(O4) are synonymous with R⁰¹ and A^(O1) to A^(O4) inthe general formula (O-1), respectively, and preferred examples thereofare also the same.

R⁰² to R⁰⁴ each independently represent a hydrogen atom, an alkyl group(preferably having from 1 to 8 carbon atoms), an aryl group (preferablyhaving from 6 to 30 carbon atoms), or a heteroaryl group (preferablyhaving from 4 to 12 carbon atoms), and may have a substituent selectedfrom the above-described Substituent Group A. R⁰² to R⁰⁴ are preferablya hydrogen atom, an alkyl group, or an aryl group, more preferably ahydrogen atom or an aryl group, and most preferably a hydrogen atom.

The glass transition temperature (Tg) of the compound represented by thegeneral formula (O-1) is preferably from 100° C. to 400° C., morepreferably from 120° C. to 400° C., and still more preferably from 140°C. to 400° C. from the viewpoint of stability at the time of storage ata high temperature, or stable operation during driving at a hightemperature or against heat generation during driving.

Specific examples of the compound represented by the general formula(O-1) are shown below, but it should not be construed that the compoundwhich is used in the present invention is limited thereto.

The compound represented by the general formula (O-1) can be synthesizedby the method described in JP-A-2001-335776. After the synthesis, it ispreferable that after performing purification by means of columnchromatography, recrystallization, reprecipitation, or the like,purification is performed by means of sublimation purification.According to the sublimation purification, not only organic impuritiescan be separated, but inorganic salts, residual solvent, moisture, andthe like can be effectively removed.

In the organic electroluminescent element according to the presentinvention, though the compound represented by the general formula (O-1)is preferably contained in the organic layer between the light emittinglayer and the cathode, it is more preferably contained in the layer onthe cathode side adjacent to the light emitting layer.

<Protective Layer>

In the present invention, the entirety of the organic electroluminescentelement may be protected by a protective layer.

For the protective layer, the detailed description in paragraphs [0169]to [0170] of JP-A-2008-270736 can also be applied to the presentinvention. Incidentally, the materials for the protective layer may beeither an inorganic material or an organic material.

<Sealing Enclosure>

For the organic electroluminescent element according to the presentinvention, the entirety of the element may be sealed using a sealingenclosure.

For the sealing enclosure, the detailed description in paragraph [0171]of JP-A-2008-270736 can be applied to the present invention.

<Driving Method>

The organic electroluminescent element according to the presentinvention can emit light by applying a direct current (it may include analternate current component, if desired) voltage (usually from 2 voltsto 15 volts) or a direct current between the anode and the cathode.

As a driving method of the organic electroluminescent element accordingto the present invention, driving methods described in JP-A-2-148687,JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234685, andJP-A-8-241047, Japanese Patent No. 2784615, and U.S. Pat. Nos. 5,828,429and 6,023,308 can be applied.

The external quantum efficiency of the organic electroluminescentelement according to the present invention is preferably 7% or more, andmore preferably 10% or more. As for the numerical value of the externalquantum efficiency, a maximum value of the external quantum efficiencyobtained when the organic electroluminescent element is driven at 20°C., or a value of the external quantum efficiency in the vicinity offrom 300 to 400 cd/m² obtained when the element is driven at 20° C. canbe employed.

The internal quantum efficiency of the organic electroluminescentelement according to the present invention is preferably 30% or more,more preferably 50% or more, and still more preferably 70% or more. Theinternal quantum efficiency of the element is calculated by dividing theexternal quantum efficiency by the light extraction efficiency. Thoughthe light extraction efficiency in usual organic EL elements is about20%, by taking into consideration the shape of a substrate, the shape ofan electrode, the film thickness of an organic layer, the film thicknessof an inorganic layer, the refractive index of an organic layer, therefractive index of an inorganic layer, or the like, it is possible toincrease the light extraction efficiency to 20% or more.

<Light Emitting Wavelength>

In the organic electroluminescent element according to the presentinvention, its light emitting wavelength is not limited. For example,the organic electroluminescent element according to the presentinvention may be used for red light emission, may be used for greenlight emission, or may be used for blue light emission among the threeprimary colors of light. Above all, from the viewpoint of luminousefficiency taking into consideration the lowest excited triplet (T₁)energy of the compound represented by the general formula (1), theorganic electroluminescent element according to the present inventionpreferably has an emission peak wavelength of from 400 to 700 nm.

Specifically, in the organic electroluminescent element according to thepresent invention, in the case of using the compound represented by thegeneral formula (1) as the host material of the light emitting layer orthe electron transporting material of the electron transporting layer orthe hole blocking layer, the emission peak wavelength of a guestmaterial is preferably from 400 to 700 nm, more preferably from 450 to650 nm, and especially preferably from 480 to 550 nm.

<Use of Organic Electroluminescent Element According to the PresentInvention>

The organic electroluminescent element according to the presentinvention can be suitably used for display elements, displays,backlights, electrophotography, illumination light sources, recordinglight sources, exposure light sources, readout light sources, signs,billboards, interior decorations, optical communications, and the like.In particular, it is preferably used for devices to be driven in aregion of high-intensity luminescence, such as a light emitting device,an illumination device, and a display device.

[Light Emitting Device]

The light emitting device according to the present invention comprisesthe organic electroluminescent element according to the presentinvention.

Next, the light emitting device according to the present invention isdescribed with reference to FIG. 2.

FIG. 2 is a cross-sectional view schematically showing one example ofthe light emitting device according to the present invention. A lightemitting device 20 in FIG. 2 is constituted of a transparent substrate 2(supporting substrate), an organic electroluminescent element 10, asealing enclosure 16, and the like.

The organic electroluminescent element 10 is constituted by laminatingan anode 3 (first electrode), an organic layer 11, and a cathode 9(second electrode) in this order on the substrate 2. In addition, aprotective layer 12 is laminated on the cathode 9, and a sealingenclosure 16 is further provided on the protective layer 12 via anadhesive layer 14. Incidentally, a part of each of the electrodes 3 and9, a diaphragm, an insulating layer, and the like are omitted in FIG. 2.

Here, a photocurable adhesive such as an epoxy resin, or a thermosettingadhesive can be used for the adhesive layer 14, and for example, athermosetting adhesive sheet can also be used as the adhesive layer 14.

The light emitting device according to the present invention is notparticularly limited in its use, and it can be used as not only anillumination device but a display device of a television set, a personalcomputer, a mobile phone, electronic paper, or the like.

[Illumination Device]

The illumination device according to the present invention comprises theorganic electroluminescent element according to the present invention.

Next, the illumination device according to the present invention isdescribed with reference to FIG. 3.

FIG. 3 is a cross-sectional view schematically showing one example ofthe illumination device according to the present invention. As shown inFIG. 3, an illumination device 40 according to the present invention isprovided with the above-described organic EL element 10 and a lightscattering member 30. More specifically, the illumination device 40 isconfigured in such a manner that the substrate 2 of the organic ELelement 10 and the light scattering member 30 are brought in contactwith each other.

Though the light scattering member 30 is not particularly limited so faras it is able to scatter light, a member obtained by dispersing fineparticles 32 in a transparent substrate 31 is used in FIG. 3. Suitableexamples of the transparent substrate 31 include a glass substrate, andsuitable examples of the fine particles 32 include transparent resinfine particles. As the glass substrate and the transparent resin fineparticles, a known product can be used for both. In such an illuminationdevice 40, when light emitted from the organic electroluminescentelement 10 is made incident onto a light incident surface 30A of thescattering member 30, the incident light is scattered by the lightscattering member 30, and the scattered light is outputted asilluminating light from a light outputting surface 30B.

[Display Device]

The display device according to the present invention comprises theorganic electroluminescent element according to the present invention.

The display device according to the present invention can be used for,for example, a display device of a television set, a personal computer,a mobile phone, electronic paper, or the like.

EXAMPLES

The characteristic features of the present invention are hereunderdescribed in more detail with reference to the following Examples andComparative Examples. The materials, use amounts, ratios, treatmentdetails, treatment procedures, and the like shown in the followingExamples and Comparative Examples can be appropriately modified so faras the gist of the present invention is not deviated. Accordingly, itshould not be construed that the scope of the present invention islimited to the specific examples shown below.

Synthesis Example 1 Synthesis of Compound 3

9H-Carbazole (23.81 g, 142.4 mmoles, 1.0 equivalent) and3-chloro-4-fluoronitrobenzene (25.00 g, 142.4 mmoles, 1.0 equivalent)were dissolved in N,N-dimethylacetamide (450 mL), to which was thenadded potassium carbonate (59.05 g, 427.2 mmoles, 3.0 equivalents), andthe mixture was heated in a nitrogen gas stream at 150° C. for 3.5hours. After allowing the reaction solution to stand for cooling,palladium acetate (1.60 g, 7.13 mmoles, 0.05 equivalents) andtricyclohexyl phosphine tetrafluoroborate (5.24 g, 14.23 mmoles, 0.1equivalents) was added thereto, followed by heating at 170° C. for onehour. After allowing the reaction solution to stand for cooling, water(3 L) was added thereto, the mixture was stirred, and the thus obtainedprecipitate was filtered off. A solid collected by means of filtrationwas dissolved in toluene, dried, and then concentrated, followed byreprecipitation with methanol. A solid was collected by means offiltration to obtain 33.20 g (81.4%) of Compound a as a brown powder.

Ammonium chloride (1.01 g, 18.88 mmoles, 0.2 equivalents), reduced iron(21.07 g, 377.3 mmoles, 4.0 equivalents), and water (94.5 mL) wereheated at 160° C. for one hour. Thereafter, isopropanol (855 mL), aceticacid (13.5 mL), and N,N′-dimethylimidazolidinone (40.5 mL) were added.Compound a (27.00 g, 94.31 mmoles, 1.0 equivalent) was added to thereaction solution, followed by heating at 90° C. for 1.5 hours. Afterallowing the reaction solution to stand for cooling, the resultant wasfiltered with Celite and extracted with ethyl acetate, followed bydrying. The resulting solution was concentrated to obtain Compound b asa dark brown solid.

Acetonitrile (270 mL) and hydrochloric acid (1.5 M aqueous solution, 136mL) were added to Compound b, and after cooling with ice to −5° C., anaqueous solution (34 mL) of sodium nitrite (7.8 g, 113.04 mmoles, 1.2equivalents) was added dropwise thereto. After stirring the mixture forone hour while cooling with ice, an aqueous solution (54 mL) ofpotassium iodide (39.12 g, 235.60 mmoles, 2.5 equivalents) was addeddropwise thereto, and the mixture was stirred for 4 hours whilegradually elevating the temperature to 80° C. After allowing thereaction solution to stand for cooling, 900 mL was added thereto, and anextracted organic layer was washed with a sodium sulfite aqueoussolution. A concentrated residue was subjected to column purification(eluant: hexane/toluene=2/1), thereby obtaining 35 g of Compound c as awhite crystal. Yield: 48.8% (two steps)

Compound c (734 mg, 2.0 mmoles, 1.0 equivalent), Compound d (951 mg, 2.2mmoles, 1.1 equivalents), tripotassium phosphate (1.27 g, 6.0 mmoles,3.0 equivalents), tris(dibenzilideneacetone)palladium (55 mg, 0.06mmoles, 0.03 equivalents),2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl (98 mg, 0.24 mmoles,0.12 equivalents), THF (20 mL), and water (10 mL) were stirred in anitrogen gas stream for 4 hours under heat-refluxing condition. Thereaction solution was allowed to stand for cooling to room temperature,ethanol was added, and a deposited crystal was then filtered. Theobtained solid was heated for dissolution in toluene, the resultant wasallowed to stand for cooling, and a deposited crystal was collected bymeans of filtration, thereby obtaining 840 mg of Illustrative Compound3. Yield: 77.0%

The result obtained by the ¹H NMR measurement of the obtainedIllustrative Compound 3 is shown in FIG. 4.

In addition, other compounds used as the host material were alsosynthesized in the same manner as that in Synthesis Example 1.

<Fabrication and Evaluation of Organic Electroluminescent Element>

It was confirmed that all of the materials used in the fabrication ofthe organic electroluminescent element were subjected to sublimationpurification, and the purity (absorption intensity area ratio at 254 nm)was confirmed to be 99.9% or more by using a high performance liquidchromatograph (TSKgel ODS-100Z, manufactured by Tosoh Corporation).

Example 1 Fabrication of Organic EL Element by Means of Deposition

A 0.5 mm-thick and 2.5 cm square glass substrate (manufactured byGeomatec Co., Ltd., surface resistance: 10Ω/□) having an ITO filmthereon was put in a cleaning container. After ultrasonic cleaning in2-propanol, the glass substrate was subjected to a UV-ozone treatmentfor 30 minutes. The following organic compound layers were depositedsequentially on this transparent anode (ITO film) by a vacuum depositionmethod.

First layer: HAT-CN: Film thickness: 10 nm

Second layer: NPD: Film thickness: 30 nm

Third layer: Light Emitting Material 1 descried below and host materialshown in the following Table 1 (mass ratio=85//15): Film thickness: 30nm

Host Material of Third Layer (Light Emitting Layer):

Comparative Compound ref-1: Compound HTM1 described in WO2007/031165

Comparative Compound ref-2: Compound 48 described in WO2010/050778

Fourth layer: TpH-18: Film thickness: 10 nm

Fifth layer: Alq: Film thickness: 40 nm

1 nm of lithium fluoride and 100 nm of metallic aluminum were depositedin this order thereon, thereby forming a cathode. At that time, apatterned mask (mask having a light emitting area of 2 mm×2 mm) wasplaced on the layer of lithium fluoride, and the metallic aluminum wasdeposited.

The obtained laminate was put in a glove box purged with a nitrogen gaswithout bringing it into contact with the atmosphere and then sealedwith a sealing can made of glass and an ultraviolet ray-curable adhesive(XNR5516HV, manufactured by Nagase-CIBA Ltd.), thereby obtaining theorganic electroluminescent element of Example 1.

Examples 2 to 5 and Comparative Examples 1 and 2

Organic electroluminescent elements of Examples 2 to 5 and ComparativeExamples 1 and 2 were produced in the same manner as that in Example 1,except that the host material and the light emitting material of thethird layer (light emitting layer) were changed as shown in thefollowing Table 1.

Incidentally, as a result of allowing the organic electroluminescentelement of each of the Examples and Comparative Examples to emit light,light emission originating in the light emitting material was obtainedin each of the organic electroluminescent elements.

In addition, in the elements of this configuration, the case of using,as the host material, the compound represented by the general formula(1) shown in the following Table 1 was excellent in both the time tohalf luminance and the time to reach 95% luminance as compared with thecase of using, as the host material, Compound 1 of JP-A-2010-87496,Compound 26 of the same patent document, or Compound 48 of the samepatent document.

<Evaluation of Element>

Each of the elements was measured for each of the time to half luminance(LT1) and the time to reach 95% luminance (LT2) when light was emittedsuch that the luminance reached 5,000 cd/m². The obtained results areshown in the following Table 1 in terms of a relative value whiledefining each of the evaluation results of the organicelectroluminescent element of Comparative Example 1 as 1.

TABLE 1 Evaluation results Element configuration Time to reach (lightemitting layer) Time to half 95% Host Light emitting luminance luminancematerial material LT1 LT2 Comparative ref-1 Light Emitting 1 1 Example 1Material 1 Comparative ref-2 Light Emitting 1.3 2.2 Example 2 Material 1Example 1 Compound 1 Light Emitting 8.4 3.5 Material 1 Example 2Compound 2 Light Emitting 9.9 4.8 Material 1 Example 3 Compound 3 LightEmitting 16.5 6.4 Material 1 Example 4 Compound 4 Light Emitting 7.5 3.8Material 1 Example 5 Compound 1 Light Emitting 7.5 3.6 Material 2

Examples 11 to 14 Fabrication (Coating) of Organic EL Element

—Preparation of Coating Solution for Forming Light Emitting Layer—

Light Emitting Material 1 (0.25% by mass) and Compound 1 (5% by mass) asthe host material were mixed with toluene (94.75% by mass) to obtainCoating Solution 1 for forming a light emitting layer.

Coating Solutions 2 to 4 for forming a light emitting layer wereprepared in the same manner as that in the preparation of the CoatingSolution 1 for forming a light emitting layer, except that the Compound1 as the host material was changed to Compounds 2 and 4, respectively.

—Fabrication of Organic Electroluminescent Element—

ITO was deposited in a thickness of 150 nm on a glass substrate at 25mm×25 mm×0.7 mm, thereby forming a film. The film was taken as atransparent supporting substrate. This transparent supporting substratewas etched and washed.

On this ITO glass substrate, 2 parts by mass of PTPDES-2 represented bythe following structural formula (manufactured by Chemipro Kasei Kaisha,Ltd., Tg=205° C.) was dissolved in 98 parts by mass of cyclohexanone forthe electronics industry use (manufactured by Kanto Chemical Co., Inc.)and spin coated in a thickness of about 40 nm (at 2,000 rpm for 20seconds). Thereafter, the coated ITO glass substrate was dried at 120°C. for 30 minutes and subjected to an annealing treatment at 160° C. for10 minutes, thereby forming a hole injecting layer.

Each of the Coating Solutions 1 to 4 for forming a light emitting layerwas spin coated in a thickness of about 40 nm on this hole injectinglayer (at 1,300 rpm, 30 seconds), thereby obtaining a light emittinglayer.

Subsequently, BAlq(bis-(2-methyl-8-quinolato)-4-(phenyl-phenolate)-aluminum(III)) wasformed in a thickness of 40 nm as an electron transporting layer on thelight emitting layer by a vacuum deposition method.

Lithium fluoride (LiF) was formed in a thickness of 1 nm as an electroninjecting layer on the electron transporting layer by a vacuumdeposition method. Metallic aluminum was further deposited in athickness of 70 nm thereon, thereby forming a cathode.

The thus-fabricated laminate was put in a globe box purged with an argongas and then sealed with a sealing can made of stainless steel and anultraviolet ray-curable adhesive (XNR5516HV, manufactured by Nagase-CIBALtd.), thereby fabricating organic electroluminescent elements ofExamples 11 to 14.

It was confirmed that in all of the obtained organic electroluminescentelements of Examples 11 to 14, good light emission was obtained.

Example 101 <Fabrication and Evaluation of Element>: Use as HostMaterial of Light Emitting Layer in Green Phosphorescent Element

It was confirmed that all of the materials used in the elementfabrication were subjected to sublimation purification, and the purity(absorption intensity area ratio at 254 nm) was confirmed to be 99.1% ormore by using a high performance liquid chromatograph (TSKgel ODS-100Z,manufactured by Tosoh Corporation).

A 0.5 mm-thick and 2.5 cm square glass substrate (manufactured byGeomatec Co., Ltd., surface resistance: 10Ω/□) having an ITO filmthereon was put in a cleaning container. After ultrasonic cleaning in2-propanol, the glass substrate was subjected to a UV-ozone treatmentfor 30 minutes. The following organic compound layers were depositedsequentially on this transparent anode (ITO film) by a vacuum depositionmethod.

First layer: Compound (A) described below: Film thickness: 10 nm

Second layer: HTL-1: Film thickness: 30 nm Third layer: Compound (1-1)and GD-1 (mass ratio: 85/15): Film thickness: 40 nm

Fourth layer: ETL-1: Film thickness: 40 nm

1 nm of lithium fluoride and 100 nm of metallic aluminum were depositedin this order thereon, thereby forming a cathode.

The obtained laminate was put in a glove box purged with a nitrogen gaswithout bringing it into contact with the atmosphere and then sealedwith a sealing can made of glass and an ultraviolet ray-curable adhesive(XNR5516HV, manufactured by Nagase-CIBA Ltd.), thereby obtaining theorganic electroluminescent element of Example 101.

Material of Hole Injecting Layer (First Layer):

Compound (A): HAT-CN

Hole Transporting Material (Second Layer):

Material of Light Emitting Layer (Third Layer):

Host material: Compound (1-1)

Light emitting material: GD-1

Electron Transporting Material (Fourth Layer): ETL-1

Examples 102 to 111 and Comparative Examples 101 and 102

Organic electroluminescent elements of Examples 102 to 111 andComparative Examples 101 and 102 were obtained in the same manner asthat in Example 101, except that in the preparation of the organicelectroluminescent element of Example 101, the Compound (1-1) of thethird layer was replaced by Compounds (1-2) to (1-11) and theabove-described Comparative Compounds ref-1 and ref-2, respectively, asshown in the following Table 2.

These elements were evaluated from the viewpoints of driving voltage,external quantum efficiency (luminous efficiency), and durability. Theobtained results are shown in the following Table 2.

(Driving Voltage)

A direct voltage was applied to each of the elements to emit light suchthat the luminance reached 1,000 cd/m². The applied voltage at that timewas defined as an index of driving voltage evaluation. The results areshown in the following Table 2, in which the case where the drivingvoltage is less than 5 V is designated as “

”; the case where the driving voltage is 5 V or more and less than 5.5 Vis designated as “◯◯”; the case where the driving voltage is 5.5 V ormore and less than 6 V is designated as “◯”; the case where the drivingvoltage is 6 V or more and less than 7 V is designated as “Δ”; and thecase where the driving voltage is 7 V or more is designated as “×”.

(External Quantum Efficiency)

A direct current voltage was applied to each of the elements by using asource measure unit 2400, manufactured by Toyo Corporation to allow theorganic electroluminescent element to emit light. The luminance wasmeasured by a luminance meter BM-8, manufactured by Topcon Corporation.The luminous spectrum and the emission peak wavelength were measured bya spectrum analyzer PMA-11, manufactured by Hamamatsu Photonics K.K. Onthe basis of these values, the external quantum efficiency at aluminance in the vicinity of 1,000 cd/m² was calculated by a luminanceconversion method.

The results are shown in the following Table 2, in which the case wherethe external quantum efficiency is 15% or more is designated as “

”; the case where the external quantum efficiency is 10% or more andless than 15% is designated as “◯”; the case where the external quantumefficiency is 8% or more and less than 10% is designated as “Δ”; and thecase where the external quantum efficiency is less than 8% is designatedas “×”.

(Durability)

A direct voltage was applied at room temperature (20° C.) to each of theelements to continuously emit light such that the luminance reached5,000 cd/m², and a time required until the luminance reached 4,000 cd/m²(time to reach 80% luminance, LT0) was defined as an index ofdurability. The results are shown in the following Table 2, in which thecase where the time is 600 hours or more is designated as “

”; the case where the time is 400 hours or more and less than 600 hoursis designated as “◯◯”; the case where the time is 200 hours or more andless than 400 hours is designated as “◯”; the case where the time is 100hours or more and less than 200 hours is designated as “Δ”; and the casewhere the time is less than 100 hours is designated as “×”.

Similarly, when each of the elements was allowed to emit light such thatthe luminance reached 5,000 cd/m², the time to half luminance (LT1) wasmeasured. The results are shown in the following Table 2, in which thecase where the time is 600 hours or more is designated as “

”; the case where the time is 400 hours or more and less than 600 hoursis designated as “◯◯”; the case where the time is 200 hours or more andless than 400 hours is designated as “◯”; the case where the time is 100hours or more and less than 200 hours is designated as “Δ”; and the casewhere the time is less than 100 hours is designated as “×”.

Similarly, when each of the elements was allowed to emit light such thatthe luminance reached 5,000 cd/m², the time to reach 95% luminance (LT2)was measured. The results are shown in the following Table 2, in whichthe case where the time is 600 hours or more is designated as “

”; the case where the time is 400 hours or more and less than 600 hoursis designated as “◯◯”; the case where the time is 200 hours or more andless than 400 hours is designated as “◯”; the case where the time is 100hours or more and less than 200 hours is designated as “Δ”; and the casewhere the time is less than 100 hours is designated as “×”.

TABLE 2 External Host Driving quantum Durability material voltageefficiency LT0 LT1 Lt2 Example 101 Compound

○○

Δ (1-1) Example 102 Compound

Δ (1-2) Example 103 Compound

○○

Δ (1-3) Example 104 Compound

Δ (1-4) Example 105 Compound

○○

Δ (1-5) Example 106 Compound ○○

○○

Δ (1-6) Example 107 Compound

○

Δ (1-7) Example 108 Compound

Δ (1-8) Example 109 Compound ○○

○○

Δ (1-9) Example 110 Compound

○○

Δ (1-10) Example 111 Compound

Δ (1-11) Comparative Comparative

○ X X X Example 101 Compound ref-1 Comparative Comparative

○ X Δ X Example 102 Compound ref-2

It was noted from the above-described Table 2 that by using the compoundrepresented by the general formula (1) as the host material (chargetransporting material) of the light emitting layer of the greenphosphorescent element, an organic electroluminescent element having aslow luminance deterioration rate at the initial stage of lighting andexcellent long-term durability.

Incidentally, it was noted that the organic electroluminescent elementfabricated in each of the Examples has an emission peak wavelength offrom 510 to 530 nm, low driving voltage, good luminous efficiency, andgood durability against the luminance reduction to 80%.

On the other hand, it was noted that when each of Comparative Compoundsref-1 and ref-2 is used as the host material of the light of the greenphosphorescent element, the luminance deterioration rate at the initialstage of lighting and the long-term durability are poor.

In addition, in the elements of this configuration, the case of using,as the host material, the compound represented by the general formula(1) in the above-described Table 2 was excellent in both the time tohalf luminance and the time to reach 95% luminance as compared with thecase of using, as the host material, Compound 1 of JP-A-2010-87496,Compound 26 of the same patent document, or Compound 48 of the samepatent document.

Examples 201 to 211 and Comparative Examples 201 and 202

Organic electroluminescent elements of Examples 201 to 211 andComparative Examples 201 and 202 were obtained in the same manner asthat in Examples 101 to 111 and Comparative Examples 101 and 102,respectively, except that in the preparation of the organicelectroluminescent elements of Examples 101 to 111 and ComparativeExamples 101 and 102, the light emitting material GD-1 of the thirdlayer was replaced by the following compound.

The thus obtained elements were evaluated in the same methods as thosein the organic electroluminescent elements of Examples 101 to 111 andComparative Examples 101 and 102. The results are shown in the followingTable 3.

TABLE 3 External Host Driving quantum Durability material voltageefficiency LT0 LT1 Lt2 Example 201 Compound

○ ○○

Δ (1-1) Example 202 Compound

○

○ (1-2) Example 203 Compound

○ ○○

Δ (1-3) Example 204 Compound

○

Δ (1-4) Example 205 Compound

○ ○○

Δ (1-5) Example 206 Compound

○

Δ (1-6) Example 207 Compound

○ ○○

Δ (1-7) Example 208 Compound

○

Δ (1-8) Example 209 Compound

○

Δ (1-9) Example 210 Compound

○

Δ (1-10) Example 211 Compound

○

Δ (1-11) Comparative Comparative

○ X X X Example 201 Compound ref-1 Comparative Comparative

○ X Δ X Example Compound 202 ref-2

It was noted from the above-described Table 3 that by using the compoundrepresented by the general formula (1) as the host material (chargetransporting material) of the light emitting layer of the greenphosphorescent element, an organic electroluminescent element having aslow luminance deterioration rate at the initial stage of lighting andexcellent long-term durability.

Incidentally, it was noted that the organic electroluminescent elementfabricated in each of the Examples has an emission peak wavelength offrom 510 to 530 nm, low driving voltage, good luminous efficiency, andgood durability against the luminance reduction to 80%.

On the other hand, it was noted that when each of Comparative Compoundsref-1 and ref-2 is used as the host material of the light of the greenphosphorescent element, the luminance deterioration rate at the initialstage of lighting and the long-term durability are poor.

In addition, in the elements of this configuration, the case of using,as the host material, the compound represented by the general formula(1) in the above-described Table 3 was excellent in both the time tohalf luminance and the time to reach 95% luminance as compared with thecase of using, as the host material, Compound 1 of JP-A-2010-87496,Compound 26 of the same patent document, or Compound 48 of the samepatent document.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

-   2: Substrate-   3: Anode-   4: Hole injecting layer-   5: Hole transporting layer-   6: Light emitting layer-   7: Hole blocking layer-   8: Electron transporting layer-   9: Cathode-   10: Organic electroluminescent element (organic EL element)-   11: Organic layer-   12: Protective layer-   14: Adhesive layer-   16: Sealing enclosure-   20: Light emitting device-   30: Light scattering member-   30A: Light incident surface-   30B: Light outputting surface-   31: Transparent substrate-   32: Fine particle-   40: Illumination device

1-22. (canceled)
 23. An organic electroluminescent element comprising asubstrate; a pair of electrodes including an anode and a cathode,disposed on the substrate; and at least one organic layer including alight emitting layer, disposed between the electrodes, wherein the lightemitting layer includes a compound represented by the following generalformula (2):

wherein: R¹ and R² each independently represent a hydrogen atom, aphenyl group, a monovalent oligoaryl group having the number of rings offrom 2 to 10, or a monovalent fused polycyclic aromatic hydrocarbongroup having the number of rings of from 2 to 6, provided that at leastone of R¹ and R² represents a monovalent oligoaryl group having thenumber of rings of from 2 to 10 or a monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6,and that the phenyl group, the monovalent oligoaryl group having thenumber of rings of from 2 to 10, and the monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6 donot have an amino group as a substituent; and R¹¹ to R¹⁸ eachindependently represent a hydrogen atom or a substituent.
 24. Theorganic electroluminescent element according to claim 23, wherein, inthe general formula (2), the group represented by R¹ or R² is a groupcontaining only one p-phenylene group.
 25. The organicelectroluminescent element according to claim 23, wherein the compoundrepresented by the general formula (2) has a T₁ energy of not less than1.77 eV and not more than 3.51 eV.
 26. The organic electroluminescentelement according to claim 23, wherein the compound represented by thegeneral formula (2) has a glass transition temperature of not less than100° C. and not more than 400° C.
 27. The organic electroluminescentelement according to claim 23, wherein the light emitting layer furthercontains a phosphorescent material.
 28. The organic electroluminescentelement according to claim 27, wherein the phosphorescent material is aniridium complex.
 29. The organic electroluminescent element according toclaim 28, wherein the iridium complex is represented by the followinggeneral formula (E-1):

wherein: Z¹ and Z² each independently represent a carbon atom or anitrogen atom; A¹ represents an atomic group for forming a 5- or6-membered heterocyclic ring together with Z¹ and the nitrogen atom; B¹represents an atomic group for forming a 5- or 6-membered heterocyclicring together with Z² and the carbon atom; (X—Y) represents amonoanionic bidentate ligand; and n_(E1) represents an integer of from 1to
 3. 30. The organic electroluminescent element according to claim 29,wherein the iridium complex represented by the general formula (E-1) isrepresented by the following general formula (E-2):

wherein: A^(E1) to A^(E8) each independently represent a nitrogen atomor C—R^(E); R^(E) represents a hydrogen atom or a substituent; (X—Y)represents a monoanionic bidentate ligand; and n_(E2) represents aninteger of from 1 to
 3. 31. The organic electroluminescent elementaccording to claim 29, wherein the iridium complex represented by thegeneral formula (E-1) is the following compound:


32. The organic electroluminescent element according to claim 23,wherein the compound represented by the general formula (2) has amolecular weight of not more than
 800. 33. The organicelectroluminescent element according to claim 23, wherein the lightemitting layer is formed by a vacuum deposition process.
 34. The organicelectroluminescent element according to claim 23, wherein the lightemitting layer is formed by a wet process.
 35. A charge transportingmaterial for an organic electroluminescent element represented by thefollowing general formula (2):

wherein: R¹ and R² each independently represent a hydrogen atom, aphenyl group, a monovalent oligoaryl group having the number of rings offrom 2 to 10, or a monovalent fused polycyclic aromatic hydrocarbongroup having the number of rings of from 2 to 6, provided that at leastone of R¹ and R² represents a monovalent oligoaryl group having thenumber of rings of from 2 to 10 or a monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6,and that the phenyl group, the monovalent oligoaryl group having thenumber of rings of from 2 to 10, and the monovalent fused polycyclicaromatic hydrocarbon group having the number of rings of from 2 to 6 donot have an amino group as a substituent; and R¹¹ to R¹⁸ eachindependently represent a hydrogen atom or a substituent.
 36. The chargetransporting material according to claim 35, wherein, in the generalformula (2), the group represented by R¹ or R² is a group containingonly one p-phenylene group.
 37. The charge transporting materialaccording to claim 35, wherein the compound represented by the generalformula (2) has a T₁ energy of not less than 1.77 eV and not more than3.51 eV.
 38. The charge transporting material according to claim 35,wherein the compound represented by the general formula (2) has a glasstransition temperature of not less than 100° C. and not more than 400°C.
 39. The charge transporting material for an organicelectroluminescent element according to claim 35, wherein the compoundrepresented by the general formula (2) has a molecular weight of notmore than
 800. 40. A light emitting device using the organicelectroluminescent element of claim
 23. 41. A display device using theorganic electroluminescent element of claim
 23. 42. An illuminationdevice using the organic electroluminescent element of claim 23.